This document contains questions and answers related to Chapter 7 - The p Block Elements in Chemistry. It discusses the general characteristics of Group 15 elements such as their electronic configuration, oxidation states, atomic size, ionization enthalpy and electronegativity. It also discusses trends in chemical reactivity within Group 15 and compares the properties of nitrogen and phosphorus. Other topics covered include industrial production of ammonia and sulfuric acid, allotropes of phosphorus, and how halogens act as strong oxidizing agents.
This document provides information on p-block elements from the chemistry class. It discusses the electronic configuration of p-block elements and their general characteristics, including variation in oxidation states, metallic and non-metallic properties, and differences in behavior between the first element of each group and other members. Specific groups like group 13 (boron family) and group 14 (carbon family) are examined in more detail regarding electronic structures, properties, and structures of compounds.
1. Nitrogen does not form pentahalides due to the absence of d-orbitals to expand its valence beyond four.
2. NH3 has stronger intermolecular hydrogen bonding than PH3, giving it a higher boiling point.
3. NO2 dimerizes to pair up its odd electron and achieve octet configuration.
The document discusses the properties of group 15 (pnicogen) elements. It describes their electronic configurations, trends in atomic radius, ionization energy, electronegativity, and oxidation states down the group. It also discusses the anomalous properties of nitrogen, allotropes of phosphorus, properties of ammonia and phosphine, and reactions of nitric acid. Key reactions in the industrial production of ammonia and nitric acid are also outlined.
Group 15 of the periodic table consists of nitrogen, phosphorus, arsenic, antimony, and bismuth. These elements can be non-metals, metalloids, or metals. They have the general electronic configuration of ns2np3 and can form compounds with oxidation states of -3, +3, and +5. The reactivity and properties of the elements change as one goes down the group due to an increase in atomic size and metallic character.
Group 15 of the periodic table contains nitrogen, phosphorus, arsenic, antimony, and bismuth. These elements share the electronic configuration of ns2np3 and can exhibit oxidation states of -3, +3, and +5, with the stability of the +5 state decreasing down the group due to the inert pair effect. The atomic radii increase down the group, while ionization energies and electronegativity decrease. Nitrogen and phosphorus are nonmetals, arsenic and antimony are metalloids, and bismuth is a metal. These trends in properties are due to the increasing size and metallic character of the elements down the group.
The document discusses p-block elements, which include groups 13 through 18 on the periodic table. Some key points:
- Most p-block elements are non-metals that can have variable oxidation states and form acidic oxides. They have high ionization potentials and electron gain enthalpies.
- Properties like metallic character and reactivity generally increase moving down each group as atomic size increases and ionization energy decreases.
- Nitrogen exhibits some anomalous properties compared to other group 15 elements due to its small size, high electronegativity, and lack of d orbitals.
The document discusses the oxidation states of elements in groups 13 and 14 of the periodic table. It notes that the +3 oxidation state is most common for group 13 but becomes less stable down the group due to the inert pair effect. For group 14, the +4 state is most common for carbon and silicon but the +2 state becomes more stable down the group also due to the inert pair effect. The document also contains sample questions and answers regarding the structures, properties, and reactions of boron- and carbon-containing compounds.
This document provides information on p-block elements from the chemistry class. It discusses the electronic configuration of p-block elements and their general characteristics, including variation in oxidation states, metallic and non-metallic properties, and differences in behavior between the first element of each group and other members. Specific groups like group 13 (boron family) and group 14 (carbon family) are examined in more detail regarding electronic structures, properties, and structures of compounds.
1. Nitrogen does not form pentahalides due to the absence of d-orbitals to expand its valence beyond four.
2. NH3 has stronger intermolecular hydrogen bonding than PH3, giving it a higher boiling point.
3. NO2 dimerizes to pair up its odd electron and achieve octet configuration.
The document discusses the properties of group 15 (pnicogen) elements. It describes their electronic configurations, trends in atomic radius, ionization energy, electronegativity, and oxidation states down the group. It also discusses the anomalous properties of nitrogen, allotropes of phosphorus, properties of ammonia and phosphine, and reactions of nitric acid. Key reactions in the industrial production of ammonia and nitric acid are also outlined.
Group 15 of the periodic table consists of nitrogen, phosphorus, arsenic, antimony, and bismuth. These elements can be non-metals, metalloids, or metals. They have the general electronic configuration of ns2np3 and can form compounds with oxidation states of -3, +3, and +5. The reactivity and properties of the elements change as one goes down the group due to an increase in atomic size and metallic character.
Group 15 of the periodic table contains nitrogen, phosphorus, arsenic, antimony, and bismuth. These elements share the electronic configuration of ns2np3 and can exhibit oxidation states of -3, +3, and +5, with the stability of the +5 state decreasing down the group due to the inert pair effect. The atomic radii increase down the group, while ionization energies and electronegativity decrease. Nitrogen and phosphorus are nonmetals, arsenic and antimony are metalloids, and bismuth is a metal. These trends in properties are due to the increasing size and metallic character of the elements down the group.
The document discusses p-block elements, which include groups 13 through 18 on the periodic table. Some key points:
- Most p-block elements are non-metals that can have variable oxidation states and form acidic oxides. They have high ionization potentials and electron gain enthalpies.
- Properties like metallic character and reactivity generally increase moving down each group as atomic size increases and ionization energy decreases.
- Nitrogen exhibits some anomalous properties compared to other group 15 elements due to its small size, high electronegativity, and lack of d orbitals.
The document discusses the oxidation states of elements in groups 13 and 14 of the periodic table. It notes that the +3 oxidation state is most common for group 13 but becomes less stable down the group due to the inert pair effect. For group 14, the +4 state is most common for carbon and silicon but the +2 state becomes more stable down the group also due to the inert pair effect. The document also contains sample questions and answers regarding the structures, properties, and reactions of boron- and carbon-containing compounds.
The document discusses the properties of group 14 elements. It notes that carbon and silicon are non-metals, germanium is a metalloid, and tin and lead are metals. It discusses their electronic configurations, atomic radii, ionization energies, electronegativity, oxidation states, and physical properties. Carbon exhibits allotropes like diamond, graphite and buckminsterfullerenes which have the same chemical composition but different physical properties. Diamond has a high melting point and hardness due to its strong covalent bonds.
This document provides study material for class 12 on p-block elements. It includes 16 questions with answers on topics like why pentahalides are more covalent than trihalides, the conditions required to maximize ammonia yield in the Haber process, and the nature of the bonds in SO2. It also lists important oxides, oxyacids, and properties of elements in the oxygen family and provides information on interhalogens, hydrogen halides, and xenon compounds.
The document discusses trends in the properties of group 15 elements of the periodic table, which include nitrogen, phosphorus, arsenic, antimony, and bismuth. It notes that ionization energy decreases and atomic/ionic radii increase down the group as atomic size increases. Nitrogen and phosphorus are nonmetals, arsenic and antimony are metalloids, and bismuth is a metal. The electronic configuration is ns2np3 and oxidation states vary between -3 to +5, with the most common being -3, +3, and +5.
- The document discusses the p-block elements in the boron family, including their occurrence, characteristics, chemical properties, and compounds.
- Boron is a rare element found in borax and boric acid, while aluminum is the most abundant metal found in bauxite. Gallium, indium, and thallium are less common and found in sulfide ores.
- The elements have the outer electronic configuration ns2np1 and exist in oxidation states of +1 and +3, with the stability of +1 increasing down the group. They form covalent bonds and react to form oxides, nitrides, halides, and hydroxides.
The document discusses the s-block elements, specifically focusing on the alkali metals. It provides an introduction and table of contents. It then discusses the electronic configuration of s-block elements and lists the alkali metals and alkaline earth metals. The next sections provide details on the characteristics properties of alkali metals, including their electronic configuration, atomic and ionic radii, ionization enthalpy, and flame coloration. Further sections describe the atomic and physical properties and chemical properties of alkali metals, including their reactivity towards air, water, hydrogen, and halogens. Applications of some alkali metals are also mentioned. References are listed at the end.
The document summarizes the properties of group 13 (boron group) elements. It discusses their electronic configurations, atomic sizes, ionization energies, electronegativity, and physical and chemical properties. The key points are:
- Group 13 includes boron, aluminum, gallium, indium, and thallium.
- Aluminum is the most abundant metal on Earth and the third most abundant element in the Earth's crust.
- The elements have an ns2np1 electronic configuration and stable +3 oxidation state that decreases down the group due to the inert pair effect.
- Atomic radii generally increase down the group except for gallium, which is smaller than aluminum due to poor d-orb
Inner Transition Element by Dr.N.H.BansodNitin Bansod
Inner Transition Element, electronic configuration lanthanide and actinide, lanthanide contraction & consequences, oxidation state, magnetic properties, ion-exchange method for separation, similarities, and differences of lanthanide and actinide
d-block elements are those in which the valence electrons enters the d orbital. d- block elements are also called transition elements. Transition elements have partially filled d orbitals.
The document discusses the physical and chemical properties of alkali metals and alkaline earth metals. It provides details about their ionization energies, reactivity, reactions with water and other substances, and color imparted to flames. Alkali metals have low melting points due to weak metallic bonding. Their reactivity increases down the group as ionization energy decreases. Alkaline earth metals have higher melting points than alkali metals due to smaller atomic size and stronger metallic bonds. Their reactivity is also less than alkali metals.
This document discusses the characteristic properties of s-block elements, which include the alkali metals (Group IA) and alkaline earth metals (Group IIA). Some key points discussed include:
- S-block elements have their outermost shell electrons in the s orbital.
- Alkali metals react vigorously with water to form alkaline hydroxides and hydrogen gas. Reactivity increases down the group.
- They form oxides, peroxides, and superoxides with oxygen. Oxidation states include -2, -1, and -1/2.
- Properties such as ionization energy, hydration energy, and metallic character generally decrease or increase moving down a group and across a period,
The document provides biographical information about Dmitri Mendeleyev, the discoverer of the periodic table. It notes that he was a Russian chemist born in 1834 who served as a professor of chemistry. In 1869, he announced the principle of periodicity of properties in chemical elements and created the first periodic table. His table arranged elements in order of atomic weight and grouped them by similar properties, allowing him to predict properties of undiscovered elements. The periodic table organized the known chemical elements and reflected recurring trends in their properties based on atomic structure.
The d-block elements have d orbitals that are progressively filled in each period. They form three transition metal series (3d, 4d, 5d) and two inner transition metal series (4f, 5f). Transition metals are defined as having incompletely filled d orbitals. They have high melting and boiling points due to strong metallic bonding. They exhibit a variety of oxidation states and can form stable complexes and interstitial compounds.
The document provides information about the elements in Group 14 of the periodic table. It begins by introducing the group and listing the elements carbon, silicon, germanium, tin, and lead. It then provides details about each element, including their physical properties, oxidation states, occurrence in nature, and important uses. The document discusses topics like allotropes of carbon, silicon semiconductor applications, germanium use in electronics, tin uses in alloys and solder, and properties of lead like its low melting point.
The document summarizes the acid-base behavior of the highest oxidation state oxides of the period 3 elements (sodium to chlorine). It finds that the oxides trend from strongly basic on the left (Na2O) to strongly acidic on the right (Cl2O7), with Al2O3 in the middle being amphoteric. Each oxide is then discussed individually in terms of its reaction with water and whether it demonstrates acidic, basic, or no reactivity.
The document discusses the d-block and f-block elements of the periodic table. It provides details about their electronic configurations, properties, and reactions. The d-block contains the transition metals whose d orbitals are filled from groups 3 to 12. The f-block contains the inner transition metals whose 4f and 5f orbitals are filled. Elements in these blocks can exhibit a variety of oxidation states and form complexes due to their electronic structure.
The document provides the electronic configurations of various ions of transition metals and lanthanides. It also provides answers to questions related to oxidation states, stability, and properties of transition metal ions and compounds. The key points are:
1) Electronic configurations of ions such as Cr3+, Cu+, Co2+, Mn2+, Pm3+, Ce4+, Lu2+, and Th4+ are given.
2) Mn2+ compounds are more stable than Fe2+ towards oxidation due to the half filled d orbital of Mn2+, making it more stable.
3) Oxidation states of transition metals increase from +2 to higher states with an increase in atomic number due to increasing number of d electrons
This document provides information about the boron family of elements. It discusses the occurrence, properties, and reactions of boron, aluminum, gallium, indium, and thallium. It focuses on boron compounds such as boranes, diborane, and borohydrides. It discusses the inert pair effect which causes the stability of lower oxidation states for heavier group 13 elements. The document also provides background on fullerenes including their discovery and C60 buckminsterfullerene.
This document discusses the properties of various p-block elements, including boron, carbon, silicon, and aluminum. It provides general information on electron configurations, atomic radii, ionization energies, and trends within groups. Specific compounds are also examined, such as borax, boronic acid, diamond, graphite, fullerenes, silicon polymers, zeolites, and aluminum alloys. Common uses of carbon, silicon, and aluminum compounds/alloys in materials and applications are described. Global warming due to excessive carbon dioxide emissions is also briefly mentioned.
This document discusses various properties of transition metals including their melting points, boiling points, atomic and ionic radii, ionization energies, oxidation states, and magnetic properties. Some key points:
- Transition metals have high melting and boiling points due to strong metallic bonds and involvement of d-orbitals in bonding. Melting points first increase to a maximum and then decrease along a period.
- Atomic/ionic radii first decrease to a minimum, then remain constant, and increase toward the end of a period as electron-electron repulsion increases.
- Ionization energies generally increase along a period as nuclear charge increases, but the effect is partly canceled by d-orbital shielding.
- Transition
This document discusses the properties and characteristics of alkaline earth metals. It begins by defining alkaline earth metals as group 2 elements with an outer electron configuration of ns2. Some key points made include:
- Alkaline earth metals have higher ionization energies than alkali metals. Ionization energy decreases down the group as atomic size increases.
- Their physical properties include being silvery-white, soft metals that are stronger oxidizers than alkali metals. They impart unique flame colors.
- Chemically, they readily react with oxygen, water and halogens. Reactivity increases down the group. They form basic hydroxides except for beryllium.
- The document also discusses trends
The document discusses the anomalous behavior of the first member of p-block elements. It is attributed to their small size, high charge to radius ratio, and unavailability of d-orbitals. As a result, the first element shows maximum covalency of 4 while others show more than 4 due to vacant d-orbitals. The first member also forms pi-pi bonds more easily than subsequent members. Hydrides of nitrogen have higher melting and boiling points than phosphorus hydrides due to hydrogen bonding in nitrogen hydrides. Oxoacids get stronger with increasing electronegativity and oxidation state of the element.
1. D and f block elements are called transition elements because their properties lie between s and p block elements and vary across the period, showing a transition in properties. They have partially filled d or f orbitals.
2. Oxidation states vary across a period but remain constant in a group because electronic configuration changes across periods but remains the same in a group.
3. Covalent halides are compounds where weak intermolecular forces are present, making them generally gases, liquids or low melting solids. Their physical properties depend on the size and polarizability of the halogen atom.
The document discusses the properties of group 14 elements. It notes that carbon and silicon are non-metals, germanium is a metalloid, and tin and lead are metals. It discusses their electronic configurations, atomic radii, ionization energies, electronegativity, oxidation states, and physical properties. Carbon exhibits allotropes like diamond, graphite and buckminsterfullerenes which have the same chemical composition but different physical properties. Diamond has a high melting point and hardness due to its strong covalent bonds.
This document provides study material for class 12 on p-block elements. It includes 16 questions with answers on topics like why pentahalides are more covalent than trihalides, the conditions required to maximize ammonia yield in the Haber process, and the nature of the bonds in SO2. It also lists important oxides, oxyacids, and properties of elements in the oxygen family and provides information on interhalogens, hydrogen halides, and xenon compounds.
The document discusses trends in the properties of group 15 elements of the periodic table, which include nitrogen, phosphorus, arsenic, antimony, and bismuth. It notes that ionization energy decreases and atomic/ionic radii increase down the group as atomic size increases. Nitrogen and phosphorus are nonmetals, arsenic and antimony are metalloids, and bismuth is a metal. The electronic configuration is ns2np3 and oxidation states vary between -3 to +5, with the most common being -3, +3, and +5.
- The document discusses the p-block elements in the boron family, including their occurrence, characteristics, chemical properties, and compounds.
- Boron is a rare element found in borax and boric acid, while aluminum is the most abundant metal found in bauxite. Gallium, indium, and thallium are less common and found in sulfide ores.
- The elements have the outer electronic configuration ns2np1 and exist in oxidation states of +1 and +3, with the stability of +1 increasing down the group. They form covalent bonds and react to form oxides, nitrides, halides, and hydroxides.
The document discusses the s-block elements, specifically focusing on the alkali metals. It provides an introduction and table of contents. It then discusses the electronic configuration of s-block elements and lists the alkali metals and alkaline earth metals. The next sections provide details on the characteristics properties of alkali metals, including their electronic configuration, atomic and ionic radii, ionization enthalpy, and flame coloration. Further sections describe the atomic and physical properties and chemical properties of alkali metals, including their reactivity towards air, water, hydrogen, and halogens. Applications of some alkali metals are also mentioned. References are listed at the end.
The document summarizes the properties of group 13 (boron group) elements. It discusses their electronic configurations, atomic sizes, ionization energies, electronegativity, and physical and chemical properties. The key points are:
- Group 13 includes boron, aluminum, gallium, indium, and thallium.
- Aluminum is the most abundant metal on Earth and the third most abundant element in the Earth's crust.
- The elements have an ns2np1 electronic configuration and stable +3 oxidation state that decreases down the group due to the inert pair effect.
- Atomic radii generally increase down the group except for gallium, which is smaller than aluminum due to poor d-orb
Inner Transition Element by Dr.N.H.BansodNitin Bansod
Inner Transition Element, electronic configuration lanthanide and actinide, lanthanide contraction & consequences, oxidation state, magnetic properties, ion-exchange method for separation, similarities, and differences of lanthanide and actinide
d-block elements are those in which the valence electrons enters the d orbital. d- block elements are also called transition elements. Transition elements have partially filled d orbitals.
The document discusses the physical and chemical properties of alkali metals and alkaline earth metals. It provides details about their ionization energies, reactivity, reactions with water and other substances, and color imparted to flames. Alkali metals have low melting points due to weak metallic bonding. Their reactivity increases down the group as ionization energy decreases. Alkaline earth metals have higher melting points than alkali metals due to smaller atomic size and stronger metallic bonds. Their reactivity is also less than alkali metals.
This document discusses the characteristic properties of s-block elements, which include the alkali metals (Group IA) and alkaline earth metals (Group IIA). Some key points discussed include:
- S-block elements have their outermost shell electrons in the s orbital.
- Alkali metals react vigorously with water to form alkaline hydroxides and hydrogen gas. Reactivity increases down the group.
- They form oxides, peroxides, and superoxides with oxygen. Oxidation states include -2, -1, and -1/2.
- Properties such as ionization energy, hydration energy, and metallic character generally decrease or increase moving down a group and across a period,
The document provides biographical information about Dmitri Mendeleyev, the discoverer of the periodic table. It notes that he was a Russian chemist born in 1834 who served as a professor of chemistry. In 1869, he announced the principle of periodicity of properties in chemical elements and created the first periodic table. His table arranged elements in order of atomic weight and grouped them by similar properties, allowing him to predict properties of undiscovered elements. The periodic table organized the known chemical elements and reflected recurring trends in their properties based on atomic structure.
The d-block elements have d orbitals that are progressively filled in each period. They form three transition metal series (3d, 4d, 5d) and two inner transition metal series (4f, 5f). Transition metals are defined as having incompletely filled d orbitals. They have high melting and boiling points due to strong metallic bonding. They exhibit a variety of oxidation states and can form stable complexes and interstitial compounds.
The document provides information about the elements in Group 14 of the periodic table. It begins by introducing the group and listing the elements carbon, silicon, germanium, tin, and lead. It then provides details about each element, including their physical properties, oxidation states, occurrence in nature, and important uses. The document discusses topics like allotropes of carbon, silicon semiconductor applications, germanium use in electronics, tin uses in alloys and solder, and properties of lead like its low melting point.
The document summarizes the acid-base behavior of the highest oxidation state oxides of the period 3 elements (sodium to chlorine). It finds that the oxides trend from strongly basic on the left (Na2O) to strongly acidic on the right (Cl2O7), with Al2O3 in the middle being amphoteric. Each oxide is then discussed individually in terms of its reaction with water and whether it demonstrates acidic, basic, or no reactivity.
The document discusses the d-block and f-block elements of the periodic table. It provides details about their electronic configurations, properties, and reactions. The d-block contains the transition metals whose d orbitals are filled from groups 3 to 12. The f-block contains the inner transition metals whose 4f and 5f orbitals are filled. Elements in these blocks can exhibit a variety of oxidation states and form complexes due to their electronic structure.
The document provides the electronic configurations of various ions of transition metals and lanthanides. It also provides answers to questions related to oxidation states, stability, and properties of transition metal ions and compounds. The key points are:
1) Electronic configurations of ions such as Cr3+, Cu+, Co2+, Mn2+, Pm3+, Ce4+, Lu2+, and Th4+ are given.
2) Mn2+ compounds are more stable than Fe2+ towards oxidation due to the half filled d orbital of Mn2+, making it more stable.
3) Oxidation states of transition metals increase from +2 to higher states with an increase in atomic number due to increasing number of d electrons
This document provides information about the boron family of elements. It discusses the occurrence, properties, and reactions of boron, aluminum, gallium, indium, and thallium. It focuses on boron compounds such as boranes, diborane, and borohydrides. It discusses the inert pair effect which causes the stability of lower oxidation states for heavier group 13 elements. The document also provides background on fullerenes including their discovery and C60 buckminsterfullerene.
This document discusses the properties of various p-block elements, including boron, carbon, silicon, and aluminum. It provides general information on electron configurations, atomic radii, ionization energies, and trends within groups. Specific compounds are also examined, such as borax, boronic acid, diamond, graphite, fullerenes, silicon polymers, zeolites, and aluminum alloys. Common uses of carbon, silicon, and aluminum compounds/alloys in materials and applications are described. Global warming due to excessive carbon dioxide emissions is also briefly mentioned.
This document discusses various properties of transition metals including their melting points, boiling points, atomic and ionic radii, ionization energies, oxidation states, and magnetic properties. Some key points:
- Transition metals have high melting and boiling points due to strong metallic bonds and involvement of d-orbitals in bonding. Melting points first increase to a maximum and then decrease along a period.
- Atomic/ionic radii first decrease to a minimum, then remain constant, and increase toward the end of a period as electron-electron repulsion increases.
- Ionization energies generally increase along a period as nuclear charge increases, but the effect is partly canceled by d-orbital shielding.
- Transition
This document discusses the properties and characteristics of alkaline earth metals. It begins by defining alkaline earth metals as group 2 elements with an outer electron configuration of ns2. Some key points made include:
- Alkaline earth metals have higher ionization energies than alkali metals. Ionization energy decreases down the group as atomic size increases.
- Their physical properties include being silvery-white, soft metals that are stronger oxidizers than alkali metals. They impart unique flame colors.
- Chemically, they readily react with oxygen, water and halogens. Reactivity increases down the group. They form basic hydroxides except for beryllium.
- The document also discusses trends
The document discusses the anomalous behavior of the first member of p-block elements. It is attributed to their small size, high charge to radius ratio, and unavailability of d-orbitals. As a result, the first element shows maximum covalency of 4 while others show more than 4 due to vacant d-orbitals. The first member also forms pi-pi bonds more easily than subsequent members. Hydrides of nitrogen have higher melting and boiling points than phosphorus hydrides due to hydrogen bonding in nitrogen hydrides. Oxoacids get stronger with increasing electronegativity and oxidation state of the element.
1. D and f block elements are called transition elements because their properties lie between s and p block elements and vary across the period, showing a transition in properties. They have partially filled d or f orbitals.
2. Oxidation states vary across a period but remain constant in a group because electronic configuration changes across periods but remains the same in a group.
3. Covalent halides are compounds where weak intermolecular forces are present, making them generally gases, liquids or low melting solids. Their physical properties depend on the size and polarizability of the halogen atom.
This is an effort to make ppt of p block elements , a topic in XII, chemistry(cbse) , whom as a tutor i have often felt students are horrified due to its large text size, long descriptipns, several information to be remembered and several reasonings to keep in mind.
Hope this ppt would solve thier problem of a thorough preparation of topic with all important aspects covered in the ppt.
Founder Dr Mona Srivastava
Masterchemclasses
Chemical bonding exercise with solutionssuresh gdvm
1. The document discusses chemical bonding and molecular structure, including the formation of chemical bonds, Lewis dot structures, octet rule, and VSEPR model.
2. Key concepts explained are the formation of ionic and covalent bonds, Lewis dot symbols, limitations of the octet rule, and molecular shapes determined by the VSEPR model for molecules like BeCl2, BCl3, and H2S.
3. Resonance is discussed for carbonate ion and why the given structures cannot be canonical forms for H3PO3.
This dissertation defense summarizes Yongjia Li's doctoral research on the design of nanostructured catalyst materials. The defense included three parts: (1) using graphene as a catalyst support for hemin, which showed activity for toluene oxidation; (2) developing bimetallic nanocatalysts including Au-Pd porous structures for alcohol oxidation and Au-Cu nanostars for CO2 reduction; and (3) a plasmonic photocatalyst using Au/Pd-TiO2 nanocomposites for tandem benzimidazole synthesis. The research demonstrated how nanostructuring and composition influences catalytic activity, selectivity, and photon absorption efficiency.
This document contains two practice tests with multiple choice questions about p-block elements for a Class 12 chemistry exam. The first test has 21 questions covering topics like nitrogen's oxidation states and reactions of ammonia, phosphine, and pentahalides. The second test also has 21 questions testing understanding of trends in reactivity, nitrogen and ammonia production, and properties of Group 15 elements. Both tests are followed by incomplete chemical equations to balance.
This document contains two practice tests with multiple choice questions about p-block elements for a Class 12 chemistry exam. The first test has 21 questions covering topics like nitrogen's oxidation states and reactions of ammonia, phosphine, and pentahalides. The second test also has 21 questions, focusing on trends in reactivity, nitrogen and ammonia production, and properties of Group 15 elements. Both tests ask students to complete several chemical reactions involving nitrogen compounds and halogens.
Hydrogen is placed separately in the periodic table due to its dual behavior. It resembles alkali metals in having one valence electron and losing an electron to form H+ ions. It also resembles halogens by gaining an electron to form H- ions and forming diatomic molecules. However, hydrogen differs from alkali metals and halogens in some properties.
The document discusses hydrogen's electronic configuration, isotopes, reasons for existing as H2 molecules, production of hydrogen by electrolysis and coal gasification, and classification of hydrides. It also answers questions on hydrogen's bonding properties and uses in welding.
شیمی آلی ۱ ( رشته شیمی)-فصل ۶-.an overview ۳.pdfAli Hamza
This document discusses how solvent affects nucleophilicity in substitution reactions. It explains that protic solvents like methanol strongly solvate anionic nucleophiles, weakening their reactivity. However, as you move down a periodic table column, the nucleophile becomes less solvated and more reactive. Polar aprotic solvents only weakly solvate nucleophiles, increasing their reactivity compared to protic solvents. Specifically, iodide shows the highest nucleophilicity in methanol despite being the weakest base, due to its large size and weak solvation.
Chemical bonding can occur via three main types: ionic, metallic, and covalent bonding. Covalent bonding involves the sharing of electron pairs between two non-metal atoms. There are three types of covalent bonds: single, double, and triple bonds which involve the sharing of one, two, or three pairs of electrons respectively. Lewis structures are diagrams that depict the bonding in covalent molecules and show the arrangement of electrons between bonded atoms. The structures help explain bonding patterns and allow for the identification of single, double, and triple bonds.
1) D-block elements are those whose last electron enters the d orbital, lying between s- and p-block elements.
2) Not all d-block elements are transition elements, which are defined as having partially filled d orbitals, while all transition elements are d-block.
3) General properties of d-block elements include high melting/boiling points due to strong metallic bonds, variable oxidation states, and many forming colored ions or complexes.
The document discusses the oxidation states of lanthanides. It states that:
1) All lanthanides most commonly exhibit a +3 oxidation state, but some can also be +2, +4, or lower states depending on electronic configuration.
2) The most stable oxidation state is generally +3 due to the strong attraction of the 4f electrons to the nucleus.
3) Elements in other oxidation states act as strong reducing or oxidizing agents as they try to attain the +3 state.
The document summarizes key points about d-block and f-block elements. It discusses the electronic configuration of transition metals and inner transition elements. It also provides information about the preparation of potassium dichromate and potassium permanganate. Some questions and answers related to the properties of transition metals and inner transition elements are also included.
This document discusses the properties of d-block elements. It explains that d-block elements have incompletely filled d orbitals which results in variable oxidation states and properties like catalytic activity, color, and paramagnetism. It also describes trends in properties across the periods and down groups, such as density increasing due to nuclear charge while size decreases, and higher melting points due to metallic and covalent bonding.
The document summarizes key concepts in polymer science including: 1) atomic structure and bonding properties that enable polymer formation, 2) the types of bonds that hold polymers together (e.g. covalent, secondary), 3) how functional groups allow monomers to link up into polymer chains, 4) the differences between thermoplastics and thermosets, and 5) ways multiple monomers can be combined in copolymers.
- Organic chemistry involves carbon-based compounds, with hydrogen usually being the second most common element. Other common elements are oxygen, nitrogen, sulfur, and halogens.
- Most bonds in organic compounds are covalent, formed through shared electron pairs between atoms. Whether bonds are ionic or covalent depends on the electro-negativity difference between bonded atoms.
- Polar covalent bonds form when there is some electro-negativity difference between atoms, causing the electron cloud to shift slightly towards the more electronegative atom. This gives the atoms partial positive or negative charges.
This document discusses trends in properties of elements across the periodic table, including:
1. Atomic and ionic radii generally increase down a group and decrease across a period, with exceptions due to electronic configuration effects like the lanthanide contraction.
2. Ionization energies decrease down a group and increase across a period as it becomes easier to remove electrons from larger atoms with more diffuse orbitals.
3. Electronegativity increases across a period as nuclear charge increases, and decreases down a group as atomic size increases.
TRANSITION METAL COMPLEXES OF CYCLOPENTADIENYL FUSED HETROCYCLES.pptxTereena1
This document discusses transition metal complexes containing cyclopentadienyl ligands. It describes the various structural types of these complexes including half-sandwich, metallocene, bent metallocene, bimetallic, and multidecker complexes. It also discusses the bonding and orbital interactions between the metal and cyclopentadienyl ligands. Finally, it briefly mentions some applications and reactivity of these complexes, noting that cyclopentadienyl ligands are versatile and important for stabilizing organometallic complexes.
1. The document contains a practice exam with 37 multiple choice questions covering concepts in thermodynamics and chemistry. The questions cover topics like ideal gases, enthalpy, entropy, spontaneity of reactions, and more.
2. For each question there are 4 possible answers labeled a-d. The correct answers are not provided.
3. The questions are intended to test understanding of fundamental thermodynamic concepts and calculations involving things like heat, work, internal energy, and state functions.
Thermodynamics is the study of heat and work, and state functions. Energy exists in various forms including heat, light, electrical, and kinetic and potential. Heat is the transfer of energy between objects due to a temperature difference. Chemical reactions can be exothermic or endothermic depending on the direction of heat transfer. The total energy in a chemical system is conserved according to the law of conservation of energy. Changes in potential and kinetic energy account for temperature changes in chemical processes.
1. Chemical thermodynamics deals with energy changes that occur during chemical reactions and processes involving chemical substances.
2. It helps determine the feasibility and extent of chemical reactions and processes under given conditions based on fundamental laws of physical chemistry.
3. Key concepts include the various types of systems (open, closed, isolated), state functions, state variables, and different thermodynamic processes (isothermal, adiabatic, isobaric, isochoric).
States of matter can exist as solids, liquids, or gases. Gases have no definite shape or volume, are highly compressible, and their molecules are far apart with weak intermolecular forces. Liquids have a definite volume but no definite shape, while solids have both a definite shape and volume. The behavior of gases is explained by gas laws such as Boyle's law, Charles's law, Avogadro's law, Dalton's law of partial pressures, Graham's law of diffusion, and the ideal gas law. Gases can be liquefied under high pressure and low temperature due to intermolecular attractions that cause real gases to deviate from ideal behavior.
Gases are composed of tiny particles that are in constant, random motion. Three properties of gases are pressure, volume, and temperature. The kinetic molecular theory and gas laws describe the relationships between these properties. The ideal gas law combines earlier gas laws relating pressure, volume, amount of gas, and temperature into a single equation.
The document discusses the characteristics and properties of gases. It defines the gaseous state as the state where intermolecular forces are at a minimum. Some key characteristics of gases include having low density, high compressibility, diffusibility, and filling their container uniformly. The document also discusses various gas laws including Boyle's law, Charles' law, Gay-Lussac's law, Avogadro's law, and the ideal gas equation. It provides the mathematical relationships and graphical representations for each gas law.
The document contains multiple choice questions about gas laws, kinetic molecular theory, and properties of gases.
1) Questions ask about calculating properties like density and pressure given temperature, volume, amount of gas, and other variables.
2) Other questions relate to concepts like effusion rates, van der Waals constants, and the relationship between temperature, pressure, volume, and number of gas molecules.
3) Graphs and diagrams are included that must be interpreted in the context of gas behavior and equations of state.
This document discusses chemical bonding and dipole moments. It contains questions about the units of dipole moment, molecules with zero dipole moment, factors that determine whether a molecule has a dipole moment, and bond properties like bond length, bond energy, and hybridization.
Chemical bonding results from the attraction between nuclei and electrons. There are three main types of bonding: ionic, covalent, and metallic. Ionic bonding involves the transfer of electrons between atoms to form ions. Covalent bonding involves the sharing of electron pairs between atoms. Metallic bonding occurs between metal atoms through delocalized valence electrons. The type of bonding determines the physical properties of the substance.
This document discusses chemical bonding and molecular structure. It begins by explaining that atoms combine through chemical bonds to form molecules and different theories have sought to explain why certain combinations are possible and what determines molecular shapes. It then summarizes Kössel-Lewis approach to chemical bonding, which proposed that atoms achieve stability by gaining or sharing electrons to attain a full outer shell of 8 electrons. Covalent bonds are formed by shared pairs of electrons between atoms. Lewis structures use dots to represent valence electrons and predict molecular geometry.
This document discusses the structure of atoms and the types of chemical bonds. It begins by defining the atom and its components like protons, electrons, and electron shells. It then explains the three main types of chemical bonds: ionic bonds formed between ions through electron transfer, covalent bonds formed by electron sharing, and metallic bonds in metals involving delocalized electrons. Some key points about each bond type are given, like ion formation and electron configuration changes. Examples of each bond type are provided. Formulas for ionic compounds and determining formula weights are also covered.
This document discusses different types of chemical bonds including ionic, covalent, and metallic bonds. It describes the formation of ionic bonds between metals and nonmetals and how ionization energy, electron affinity, and lattice energy contribute to the energetics of ionic bonding. Covalent bonding is explained as the sharing of electrons between nonmetals. Factors that determine bond polarity like electronegativity are also covered. The document provides details on writing Lewis structures, accounting for valence electrons and formal charges. Exceptions to the octet rule for molecules with odd numbers of electrons, incomplete octets, and expanded octets are explained.
Chemical bonding occurs when atoms combine to form molecules or ionic compounds to achieve stable electronic configurations. There are several types of bonds including ionic bonds, covalent bonds, and coordinate bonds. Ionic bonds form when electrons are transferred from electropositive atoms to electronegative atoms, resulting in oppositely charged ions that are attracted to each other. Covalent bonds form through the sharing of electron pairs between atoms. Coordinate bonds form through the interaction of a Lewis acid and base where one species provides a pair of electrons. Chemical bonds provide stability and determine many properties of substances.
The document discusses the evolution and development of the periodic table. It describes early classification systems like Dobereiner's law of triads and Newlands' law of octaves. It then focuses on Mendeleev's periodic table from 1869, which was the first significant classification based on atomic mass. The modern periodic table is based on atomic number rather than mass, resolving anomalies in Mendeleev's table. It discusses periodic trends in properties like atomic radius and how the periodic table is structured into blocks, periods and groups.
The document discusses periodic trends in elemental properties. It explains that Dmitri Mendeleev was the first to organize elements in a periodic table based on their properties. Elements in the same group have similar properties due to their valence electrons. Atomic radius generally decreases moving left to right across a period and increases moving down a group due to electron shielding. Ionization energy increases as atomic radius decreases. Electron affinity is exothermic when gaining electrons fills an orbital. Metallic character decreases and electronegativity increases moving from left to right. Cations are smaller than their parent atoms while anions are larger.
This document provides information on the classification of elements and various periodic properties like atomic size, ionization energy, electron affinity and electronegativity. It discusses the trends in these properties across periods and groups and exceptions to trends. It also explains concepts like ionic size, isoelectronic species, ionization energies, electron affinities, Pauling and Mulliken scales of electronegativity and valency. Sample problems are provided at the end to test the understanding of these concepts.
This document summarizes key concepts in atomic structure:
1. It outlines the early theories of Dalton, Thomson, Rutherford, and Bohr, which proposed that atoms are made of fundamental particles and have small, dense nuclei surrounded by orbiting electrons.
2. It describes experiments that discovered the electron and properties of cathode rays. Rutherford's gold foil experiment provided evidence for a small, dense nucleus.
3. Quantum theory concepts like Planck's quantum hypothesis, Bohr's model of electron orbits, and de Broglie's matter waves are introduced along with equations relating wavelength, frequency and energy of photons.
This document provides an overview of basic chemistry concepts. It begins by classifying matter as either mixtures or pure substances, with pure substances further divided into elements and compounds. Elements contain only one type of atom, while compounds contain two or more different types of atoms combined in fixed ratios. The three common states of matter - solids, liquids, and gases - are described based on how tightly or loosely the particles are packed. Key concepts like the mole, molar mass, empirical and molecular formulas are also introduced. Measurement units commonly used in chemistry like grams, meters, and moles are defined according to the International System of Units.
Chemistry involves experimentally studying the physical and chemical properties of substances and measuring them precisely. Measurements have some uncertainty depending on the skill of the person and instrument used. Significant figures refer to the digits that convey the accuracy of a measurement based on the instrument's least count. Chemical quantities and reactions follow various laws including the law of conservation of mass, law of definite proportions, law of multiple proportions, and Gay-Lussac's law of gas volumes in chemical combinations. Dalton's atomic hypothesis provided a theoretical basis for these laws by proposing that elements are made of atoms that combine in fixed ratios to form compounds.
The document provides an overview of organic reactions, describing common reaction types like addition, elimination, substitution, and rearrangement. It explains that organic reactions can be described in terms of their mechanisms, which involve the making and breaking of covalent bonds. Polar reactions occur through the attack of electron-rich nucleophiles on electron-deficient electrophilic sites, while radical reactions proceed through the formation, reaction, and termination of free radicals. Curved arrows are used to indicate the flow of electrons between reagents in reaction mechanisms.
Physiology and chemistry of skin and pigmentation, hairs, scalp, lips and nail, Cleansing cream, Lotions, Face powders, Face packs, Lipsticks, Bath products, soaps and baby product,
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Assessment and Planning in Educational technology.pptxKavitha Krishnan
In an education system, it is understood that assessment is only for the students, but on the other hand, the Assessment of teachers is also an important aspect of the education system that ensures teachers are providing high-quality instruction to students. The assessment process can be used to provide feedback and support for professional development, to inform decisions about teacher retention or promotion, or to evaluate teacher effectiveness for accountability purposes.
Executive Directors Chat Leveraging AI for Diversity, Equity, and InclusionTechSoup
Let’s explore the intersection of technology and equity in the final session of our DEI series. Discover how AI tools, like ChatGPT, can be used to support and enhance your nonprofit's DEI initiatives. Participants will gain insights into practical AI applications and get tips for leveraging technology to advance their DEI goals.
বাংলাদেশের অর্থনৈতিক সমীক্ষা ২০২৪ [Bangladesh Economic Review 2024 Bangla.pdf] কম্পিউটার , ট্যাব ও স্মার্ট ফোন ভার্সন সহ সম্পূর্ণ বাংলা ই-বুক বা pdf বই " সুচিপত্র ...বুকমার্ক মেনু 🔖 ও হাইপার লিংক মেনু 📝👆 যুক্ত ..
আমাদের সবার জন্য খুব খুব গুরুত্বপূর্ণ একটি বই ..বিসিএস, ব্যাংক, ইউনিভার্সিটি ভর্তি ও যে কোন প্রতিযোগিতা মূলক পরীক্ষার জন্য এর খুব ইম্পরট্যান্ট একটি বিষয় ...তাছাড়া বাংলাদেশের সাম্প্রতিক যে কোন ডাটা বা তথ্য এই বইতে পাবেন ...
তাই একজন নাগরিক হিসাবে এই তথ্য গুলো আপনার জানা প্রয়োজন ...।
বিসিএস ও ব্যাংক এর লিখিত পরীক্ষা ...+এছাড়া মাধ্যমিক ও উচ্চমাধ্যমিকের স্টুডেন্টদের জন্য অনেক কাজে আসবে ...
This presentation was provided by Steph Pollock of The American Psychological Association’s Journals Program, and Damita Snow, of The American Society of Civil Engineers (ASCE), for the initial session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session One: 'Setting Expectations: a DEIA Primer,' was held June 6, 2024.
it describes the bony anatomy including the femoral head , acetabulum, labrum . also discusses the capsule , ligaments . muscle that act on the hip joint and the range of motion are outlined. factors affecting hip joint stability and weight transmission through the joint are summarized.
Thinking of getting a dog? Be aware that breeds like Pit Bulls, Rottweilers, and German Shepherds can be loyal and dangerous. Proper training and socialization are crucial to preventing aggressive behaviors. Ensure safety by understanding their needs and always supervising interactions. Stay safe, and enjoy your furry friends!
A workshop hosted by the South African Journal of Science aimed at postgraduate students and early career researchers with little or no experience in writing and publishing journal articles.
How to Fix the Import Error in the Odoo 17Celine George
An import error occurs when a program fails to import a module or library, disrupting its execution. In languages like Python, this issue arises when the specified module cannot be found or accessed, hindering the program's functionality. Resolving import errors is crucial for maintaining smooth software operation and uninterrupted development processes.
1. Class XII
Chapter 7 – The p Block Elements
Chemistry
Question 7.1:
Discuss the general characteristics of Group 15 elements with reference to their
electronic
configuration,
oxidation
state,
atomic
size,
ionisation
enthalpy
and
electronegativity.
Answer
General trends in group 15 elements
(i) Electronic configuration: All the elements in group 15 have 5 valence electrons.
Their general electronic configuration is ns2 np3.
(ii) Oxidation states: All these elements have 5 valence electrons and require three
more electrons to complete their octets. However, gaining electrons is very difficult as
the nucleus will have to attract three more electrons. This can take place only with
nitrogen as it is the smallest in size and the distance between the nucleus and the
valence shell is relatively small. The remaining elements of this group show a formal
oxidation state of −3 in their covalent compounds. In addition to the −3 state, N and P
also show −1 and −2 oxidation states.
All the elements present in this group show +3 and +5 oxidation states. However, the
stability of +5 oxidation state decreases down a group, whereas the stability of +3
oxidation state increases. This happens because of the inert pair effect.
(iii) Ionization energy and electronegativity
First ionization decreases on moving down a group. This is because of increasing atomic
sizes. As we move down a group, electronegativity decreases, owing to an increase in
size.
(iv) Atomic size: On moving down a group, the atomic size increases. This increase in
the atomic size is attributed to an increase in the number of shells.
Question 7.2:
Why does the reactivity of nitrogen differ from phosphorus?
Answer
Nitrogen is chemically less reactive. This is because of the high stability of its molecule,
N2. In N2, the two nitrogen atoms form a triple bond. This triple bond has very high bond
strength, which is very difficult to break. It is because of nitrogen’s small size that it is
able to form pπ−pπ bonds with itself. This property is not exhibited by atoms such as
phosphorus. Thus, phosphorus is more reactive than nitrogen.
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2. Class XII
Chapter 7 – The p Block Elements
Chemistry
Question 7.3:
Discuss the trends in chemical reactivity of group 15 elements.
Answer
General trends in chemical properties of group − 15
(i) Reactivity towards hydrogen:
The elements of group 15 react with hydrogen to form hydrides of type EH3, where E =
N, P, As, Sb, or Bi. The stability of hydrides decreases on moving down from NH3 to BiH3.
(ii) Reactivity towards oxygen:
The elements of group 15 form two types of oxides: E2O3 and E2O5, where E = N, P, As,
Sb, or Bi. The oxide with the element in the higher oxidation state is more acidic than
the other. However, the acidic character decreases on moving down a group.
(iii) Reactivity towards halogens:
The group 15 elements react with halogens to form two series of salts: EX3 and EX5.
However, nitrogen does not form NX5 as it lacks the d-orbital. All trihalides (except NX3)
are stable.
(iv) Reactivity towards metals:
The group 15 elements react with metals to form binary compounds in which metals
exhibit −3 oxidation states.
Question 7.4:
Why does NH3 form hydrogen bond but PH3 does not?
Answer
Nitrogen is highly electronegative as compared to phosphorus. This causes a greater
attraction of electrons towards nitrogen in NH3 than towards phosphorus in PH3. Hence,
the extent of hydrogen bonding in PH3 is very less as compared to NH3.
Question 7.5:
How is nitrogen prepared in the laboratory? Write the chemical equations of the
reactions involved.
Answer
An aqueous solution of ammonium chloride is treated with sodium nitrite.
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Chapter 7 – The p Block Elements
Chemistry
NO and HNO3 are produced in small amounts. These are impurities that can be removed
on passing nitrogen gas through aqueous sulphuric acid, containing potassium
dichromate.
Question 7.6:
How is ammonia manufactured industrially?
Answer
Ammonia is prepared on a large-scale by the Haber’s process.
The optimum conditions for manufacturing ammonia are:
(i) Pressure (around 200 × 105 Pa)
(ii) Temperature (4700 K)
(iii) Catalyst such as iron oxide with small amounts of Al2O3 and K2O
Question 7.7:
Illustrate how copper metal can give different products on reaction with HNO3.
Answer
Concentrated nitric acid is a strong oxidizing agent. It is used for oxidizing most metals.
The products of oxidation depend on the concentration of the acid, temperature, and
also on the material undergoing oxidation.
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4. Class XII
Chapter 7 – The p Block Elements
Chemistry
Question 7.8:
Give the resonating structures of NO2 and N2O5.
Answer
(1)
(2)
Question 7.9:
The HNH angle value is higher than HPH, HAsH and HSbH angles. Why? [Hint: Can be
explained on the basis of sp3 hybridisation in NH3 and only s−p bonding between
hydrogen and other elements of the group].
Answer
Hydride NH3 PH3 AsH3 SbH3
H−M−H angle 107° 92° 91° 90°
The above trend in the H−M−H bond angle can be explained on the basis of the
electronegativity of the central atom. Since nitrogen is highly electronegative, there is
high electron density around nitrogen. This causes greater repulsion between the
electron pairs around nitrogen, resulting in maximum bond angle. We know that
electronegativity decreases on moving down a group. Consequently, the repulsive
interactions between the electron pairs decrease, thereby decreasing the H−M−H bond
angle.
Question 7.10:
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5. Class XII
Chapter 7 – The p Block Elements
Chemistry
Why does R3P=O exist but R3N=O does not (R = alkyl group)?
Answer
N (unlike P) lacks the d-orbital. This restricts nitrogen to expand its coordination number
beyond four. Hence, R3N=O does not exist.
Question 7.11:
Explain why NH3 is basic while BiH3 is only feebly basic.
Answer
NH3 is distinctly basic while BiH3 is feebly basic.
Nitrogen has a small size due to which the lone pair of electrons is concentrated in a
small region. This means that the charge density per unit volume is high. On moving
down a group, the size of the central atom increases and the charge gets distributed
over a large area decreasing the electron density. Hence, the electron donating capacity
of group 15 element hydrides decreases on moving down the group.
Question 7.12:
Nitrogen exists as diatomic molecule and phosphorus as P4. Why?
Answer
Nitrogen owing to its small size has a tendency to form pπ−pπ multiple bonds with itself.
Nitrogen thus forms a very stable diatomic molecule, N2. On moving down a group, the
tendency to form pπ−pπ bonds decreases (because of the large size of heavier
elements). Therefore, phosphorus (like other heavier metals) exists in the P4 state.
Question 7.13:
Write main differences between the properties of white phosphorus and red phosphorus.
Answer
White phosphorus
Red Phosphorus
It is a soft and waxy
It is a hard and crystalline solid, without any smell.
solid.
It
possesses
a
garlic smell.
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6. Class XII
Chapter 7 – The p Block Elements
It is poisonous.
It is non-poisonous.
It is insoluble in water
It is insoluble in both water and carbon disulphide.
but
soluble
in
Chemistry
carbon
disulphide.
It
undergoes
It is relatively less reactive.
spontaneous combustion
in air.
In both solid and vapour
It exists as a chain of tetrahedral P4 units.
states, it exists as a P4
molecule.
Question 7.14:
Why does nitrogen show catenation properties less than phosphorus?
Answer
Catenation is much more common in phosphorous compounds than in nitrogen
compounds. This is because of the relative weakness of the N−N single bond as
compared to the P−P single bond. Since nitrogen atom is smaller, there is greater
repulsion of electron density of two nitrogen atoms, thereby weakening the N−N single
bond.
Question 7.15:
Give the disproportionation reaction of H3PO3.
Answer
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7. Class XII
Chapter 7 – The p Block Elements
Chemistry
On heating, orthophosphorus acid (H3PO3) disproportionates to give orthophosphoric acid
(H3PO4) and phosphine (PH3). The oxidation states of P in various species involved in the
reaction are mentioned below.
Question 7.16:
Can PCl5 act as an oxidising as well as a reducing agent? Justify.
Answer
PCl5 can only act as an oxidizing agent. The highest oxidation state that P can show is
+5. In PCl5, phosphorus is in its highest oxidation state (+5). However, it can decrease
its oxidation state and act as an oxidizing agent.
Question 7.17:
Justify the placement of O, S, Se, Te and Po in the same group of the periodic table in
terms of electronic configuration, oxidation state and hydride formation.
Answer
The elements of group 16 are collectively called chalcogens.
(i) Elements of group 16 have six valence electrons each. The general electronic
configuration of these elements is ns2 np4, where n varies from 2 to 6.
(ii) Oxidation state:
As these elements have six valence electrons (ns2 np4), they should display an oxidation
state of −2. However, only oxygen predominantly shows the oxidation state of −2 owing
to its high electronegativity. It also exhibits the oxidation state of −1 (H2O2), zero (O2),
and +2 (OF2). However, the stability of the −2 oxidation state decreases on moving
down a group due to a decrease in the electronegativity of the elements. The heavier
elements of the group show an oxidation state of +2, +4, and +6 due to the availability
of d-orbitals.
(iii) Formation of hydrides:
These elements form hydrides of formula H2E, where E = O, S, Se, Te, PO. Oxygen and
sulphur also form hydrides of type H2E2. These hydrides are quite volatile in nature.
Question 7.18:
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8. Class XII
Chapter 7 – The p Block Elements
Chemistry
Why is dioxygen a gas but sulphur a solid?
Answer
Oxygen is smaller in size as compared to sulphur. Due to its smaller size, it can
effectively form pπ−pπ bonds and form O2 (O==O) molecule. Also, the intermolecular
forces in oxygen are weak van der Wall’s, which cause it to exist as gas. On the other
hand, sulphur does not form M2 molecule but exists as a puckered structure held
together by strong covalent bonds. Hence, it is a solid.
Question 7.19:
Knowing the electron gain enthalpy values for O → O− and O → O2− as −141
and 702 kJ mol−1 respectively, how can you account for the formation of a
large number of oxides having O2− species and not O−?
(Hint: Consider lattice energy factor in the formation of compounds).
Answer
Stability of an ionic compound depends on its lattice energy. More the lattice energy of a
compound, more stable it will be.
Lattice energy is directly proportional to the charge carried by an ion. When a metal
combines with oxygen, the lattice energy of the oxide involving O2− ion is much more
than the oxide involving O− ion. Hence, the oxide having O2− ions are more stable than
oxides having O−. Hence, we can say that formation of O2− is energetically more
favourable than formation of O−.
Question 7.20:
Which aerosols deplete ozone?
Answer
Freons or chlorofluorocarbons (CFCs) are aerosols that accelerate the depletion of ozone.
In the presence of ultraviolet radiations, molecules of CFCs break down to form chlorinefree radicals that combine with ozone to form oxygen.
Question 7.21:
Describe the manufacture of H2SO4 by contact process?
Answer
Sulphuric acid is manufactured by the contact process. It involves the following steps:
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9. Class XII
Chapter 7 – The p Block Elements
Chemistry
Step (i):
Sulphur or sulphide ores are burnt in air to form SO2.
Step (ii):
By a reaction with oxygen, SO2 is converted into SO3 in the presence of V2O5 as a
catalyst.
Step (iii):
SO3 produced is absorbed on H2SO4 to give H2S2O7 (oleum).
This oleum is then diluted to obtain H2SO4 of the desired concentration.
In practice, the plant is operated at 2 bar (pressure) and 720 K (temperature). The
sulphuric acid thus obtained is 96-98% pure.
Question 7.22:
How is SO2 an air pollutant?
Answer
Sulphur dioxide causes harm to the environment in many ways:
1. It combines with water vapour present in the atmosphere to form sulphuric acid. This
causes acid rain. Acid rain damages soil, plants, and buildings, especially those made of
marble.
2. Even in very low concentrations, SO2 causes irritation in the respiratory tract. It
causes throat and eye irritation and can also affect the larynx to cause breathlessness.
3. It is extremely harmful to plants. Plants exposed to sulphur dioxide for a long time
lose colour from their leaves. This condition is known as chlorosis. This happens because
the formation of chlorophyll is affected by the presence of sulphur dioxide.
Question 7.23:
Why are halogens strong oxidising agents?
Answer
The general electronic configuration of halogens is np5, where n = 2-6. Thus, halogens
need only one more electron to complete their octet and to attain the stable noble gas
configuration. Also, halogens are highly electronegative with low dissociation energies
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10. Class XII
Chapter 7 – The p Block Elements
Chemistry
and high negative electron gain enthalpies. Therefore, they have a high tendency to gain
an electron. Hence, they act as strong oxidizing agents.
Question 7.24:
Explain why fluorine forms only one oxoacid, HOF.
Answer
Fluorine forms only one oxoacid i.e., HOF because of its high electronegativity and small
size.
Question 7.25:
Explain why inspite of nearly the same electronegativity, oxygen forms hydrogen
bonding while chlorine does not.
Answer
Both chlorine and oxygen have almost the same electronegativity values, but chlorine
rarely forms hydrogen bonding. This is because in comparison to chlorine, oxygen has a
smaller size and as a result, a higher electron density per unit volume.
Question 7.26:
Write two uses of ClO2.
Answer
Uses of ClO2:
(i) It is used for purifying water.
(ii) It is used as a bleaching agent.
Question 7.27:
Why are halogens coloured?
Answer
Almost all halogens are coloured. This is because halogens absorb radiations in the
visible region. This results in the excitation of valence electrons to a higher energy
region. Since the amount of energy required for excitation differs for each halogen, each
halogen displays a different colour.
Question 7.28:
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11. Class XII
Chapter 7 – The p Block Elements
Chemistry
Write the reactions of F2 and Cl2 with water.
Answer
(i)
(ii)
Question 7.29:
How can you prepare Cl2 from HCl and HCl from Cl2? Write reactions only.
Answer
(i) Cl2 can be prepared from HCl by Deacon’s process.
(ii) HCl can be prepared from Cl2 on treating it with water.
Question 7.30:
What inspired N. Bartlett for carrying out reaction between Xe and PtF6?
Answer
Neil Bartlett initially carried out a reaction between oxygen and PtF6. This resulted in the
formation of a red compound,
.
Later, he realized that the first ionization energy of oxygen (1175 kJ/mol) and Xe (1170
kJ/mol) is almost the same. Thus, he tried to prepare a compound with Xe and PtF6. He
was successful and a red-coloured compound,
was formed.
Question 7.31:
What are the oxidation states of phosphorus in the following:
(i) H3PO3 (ii) PCl3 (iii) Ca3P2
(iv) Na3PO4 (v) POF3?
Answer
.
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Chapter 7 – The p Block Elements
Chemistry
(i) H3PO3
(ii) PCl3
(iii) Ca3P2
(iv) Na3PO4
(v) POF3
Question 7.32:
Write balanced equations for the following:
(i) NaCl is heated with sulphuric acid in the presence of MnO2.
(ii) Chlorine gas is passed into a solution of NaI in water.
Answer
(i)
(ii)
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13. Class XII
Chapter 7 – The p Block Elements
Chemistry
Question 7.33:
How are xenon fluorides XeF2, XeF4 and XeF6 obtained?
Answer
XeF2, XeF4, and XeF6 are obtained by a direct reaction between Xe and F2. The condition
under which the reaction is carried out determines the product.
Question 7.34:
With what neutral molecule is ClO− isoelectronic? Is that molecule a Lewis base?
Answer
ClO− is isoelectronic to ClF. Also, both species contain 26 electrons in all as shown.
Total electrons ClO− = 17 + 8 + 1 = 26
In ClF = 17 + 9 = 26
ClF acts like a Lewis base as it accepts electrons from F to form ClF3.
Question 7.35:
How are XeO3 and XeOF4 prepared?
Answer
(i) XeO3 can be prepared in two ways as shown.
(ii) XeOF4 can be prepared using XeF6.
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14. Class XII
Chapter 7 – The p Block Elements
Chemistry
Question 7.36:
Arrange the following in the order of property indicated for each set:
(i) F2, Cl2, Br2, I2 - increasing bond dissociation enthalpy.
(ii) HF, HCl, HBr, HI - increasing acid strength.
(iii) NH3, PH3, AsH3, SbH3, BiH3 − increasing base strength.
Answer
(i) Bond dissociation energy usually decreases on moving down a group as the atomic
size increases. However, the bond dissociation energy of F2 is lower than that of Cl2 and
Br2. This is due to the small atomic size of fluorine. Thus, the increasing order for bond
dissociation energy among halogens is as follows:
I2 < F2 < Br2 < Cl2
(ii) HF < HCl < HBr < HI
The bond dissociation energy of H-X molecules where X = F, Cl, Br, I, decreases with an
increase in the atomic size. Since H-I bond is the weakest, HI is the strongest acid.
(iii) BiH3 ≤ SbH3 < AsH3 < PH3 < NH3
On moving from nitrogen to bismuth, the size of the atom increases while the electron
density on the atom decreases. Thus, the basic strength decreases.
Question 7.37:
Which one of the following does not exist?
(i) XeOF4 (ii) NeF2
(iii) XeF2 (iv) XeF6
Answer
NeF2 does not exist.
Question 7.38:
Give the formula and describe the structure of a noble gas species which is isostructural
with:
(i)
(ii)
(iii)
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15. Class XII
Chapter 7 – The p Block Elements
Chemistry
Answer
(i)
XeF4 is isoelectronic with
and has square planar geometry.
(ii)
XeF2 is isoelectronic to
and has a linear structure.
(iii)
XeO3 is isostructural to
and has a pyramidal molecular structure.
Question 7.39:
Why do noble gases have comparatively large atomic sizes?
Answer
Noble gases do not form molecules. In case of noble gases, the atomic radii corresponds
to van der Waal’s radii. On the other hand, the atomic radii of other elements correspond
to their covalent radii. By definition, van der Waal’s radii are larger than covalent radii. It
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16. Class XII
Chapter 7 – The p Block Elements
Chemistry
is for this reason that noble gases are very large in size as compared to other atoms
belonging to the same period.
Question 7.40:
List the uses of Neon and argon gases.
Answer
Uses of neon gas:
(i) It is mixed with helium to protect electrical equipments from high voltage.
(ii) It is filled in discharge tubes with characteristic colours.
(iii) It is used in beacon lights.
Uses of Argon gas:
(i) Argon along with nitrogen is used in gas-filled electric lamps. This is because Ar is
more inert than N.
(ii) It is usually used to provide an inert temperature in a high metallurgical process.
(iii) It is also used in laboratories to handle air-sensitive substances.
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17. Class XII
Chapter 7 – The p Block Elements
Chemistry
Text solution
Question 7.1:
Why are pentahalides more covalent than trihalides?
Answer
In pentahalides, the oxidation state is +5 and in trihalides, the oxidation state is +3.
Since the metal ion with a high charge has more polarizing power, pentahalides are
more covalent than trihalides.
Question 7.2:
Why is BiH3 the strongest reducing agent amongst all the hydrides of
Group 15 elements?
Answer
As we move down a group, the atomic size increases and the stability of the hydrides of
group 15 elements decreases. Since the stability of hydrides decreases on moving from
NH3 to BiH3, the reducing character of the hydrides increases on moving from NH3 to
BiH3.
Question 7.3:
Why is N2 less reactive at room temperature?
Answer
The two N atoms in N2 are bonded to each other by very strong triple covalent bonds.
The bond dissociation energy of this bond is very high. As a result, N2 is less reactive at
room temperature.
Question 7.4:
Mention the conditions required to maximise the yield of ammonia.
Answer
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18. Class XII
Chapter 7 – The p Block Elements
Chemistry
Ammonia is prepared using the Haber’s process. The yield of ammonia can be maximized
under the following conditions:
(i) High pressure (∼ 200 atm)
(ii) A temperature of ∼700 K
(iii) Use of a catalyst such as iron oxide mixed with small amounts of K2O and Al2O3
Question 7.5:
How does ammonia react with a solution of Cu2+?
Answer
NH3 acts as a Lewis base. It donates its electron pair and forms a linkage with metal ion.
Question 7.6:
What is the covalence of nitrogen in N2O5?
Answer
From the structure of N2O5, it is evident that the covalence of nitrogen is 4.
Question 7.7:
Bond angle in
is higher than that in PH3. Why?
Answer
In PH3, P is sp3 hybridized. Three orbitals are involved in bonding with three hydrogen
atoms and the fourth one contains a lone pair. As lone pair-bond pair repulsion is
stronger than bond pair-bond pair repulsion, the tetrahedral shape associated with sp3
bonding is changed to pyramidal. PH3 combines with a proton to form
lone pair is absent. Due to the absence of lone pair in
pair repulsion. Hence, the bond angle in
in which the
, there is no lone pair-bond
is higher than the bond angle in PH3.
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19. Class XII
Chapter 7 – The p Block Elements
Chemistry
Question 7.8:
What happens when white phosphorus is heated with concentrated NaOH solution in an
inert atmosphere of CO2?
Answer
White phosphorous dissolves in boiling NaOH solution (in a CO2 atmosphere) to give
phosphine, PH3.
Question 7.9:
What happens when PCl5 is heated?
Answer
All the bonds that are present in PCl5 are not similar. It has three equatorial and two
axial bonds. The equatorial bonds are stronger than the axial ones. Therefore, when PCl5
is heated strongly, it decomposes to form PCl3.
Question 7.10:
Write a balanced equation for the hydrolytic reaction of PCl5 in heavy water.
Answer
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20. Class XII
Chapter 7 – The p Block Elements
Chemistry
Question 7.11:
What is the basicity of H3PO4?
Answer
H3PO4
Since there are three OH groups present in H3PO4, its basicity is three i.e., it is a tribasic
acid.
Question 7.12:
What happens when H3PO3 is heated?
Answer
H3PO3, on heating, undergoes disproportionation reaction to form PH3 and H3PO4. The
oxidation numbers of P in H3PO3, PH3, and H3PO4 are +3, −3, and +5 respectively. As the
oxidation number of the same element is decreasing and increasing during a particular
reaction, the reaction is a disproportionation reaction.
Question 7.13:
List the important sources of sulphur.
Answer
Sulphur mainly exists in combined form in the earth’s crust primarily as sulphates
[gypsum (CaSO4.2H2O), Epsom salt (MgSO4.7H2O), baryte (BaSO4)] and sulphides
[(galena (PbS), zinc blends (ZnS), copper pyrites (CuFeS2)].
Question 7.14:
Write the order of thermal stability of the hydrides of Group 16 elements.
Answer
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21. Class XII
Chapter 7 – The p Block Elements
Chemistry
The thermal stability of hydrides decreases on moving down the group. This is due to a
decrease in the bond dissociation enthalpy (H−E) of hydrides on moving down the
group.
Therefore,
Question 7.15:
Why is H2O a liquid and H2S a gas?
Answer
H2O
has
oxygen
as
the
central
atom.
Oxygen
has
smaller
size
and
higher
electronegativity as compared to sulphur. Therefore, there is extensive hydrogen
bonding in H2O, which is absent in H2S. Molecules of H2S are held together only by weak
van der Waal’s forces of attraction.
Hence, H2O exists as a liquid while H2S as a solid.
Question 7.16:
Which of the following does not react with oxygen directly?
Zn, Ti, Pt, Fe
Answer
Pt is a noble metal and does not react very easily. All other elements, Zn, Ti, Fe, are
quite reactive. Hence, oxygen does not react with platinum (Pt) directly.
Question 7.17:
Complete the following reactions:
(i) C2H4 + O2 →
(ii) 4Al + 3 O2 →
Answer
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22. Class XII
Chapter 7 – The p Block Elements
Chemistry
(i)
(ii)
Question 7.18:
Why does O3 act as a powerful oxidising agent?
Answer
Ozone is not a very stable compound under normal conditions and decomposes readily
on heating to give a molecule of oxygen and nascent oxygen. Nascent oxygen, being a
free radical, is very reactive.
Therefore, ozone acts as a powerful oxidising agent.
Question 7.19:
How is O3 estimated quantitatively?
Answer
Quantitatively, ozone can be estimated with the help of potassium iodide. When ozone is
made to react with potassium iodide solution buffered with a borate buffer (pH 9.2),
iodine is liberated. This liberated iodine can be titrated against a standard solution of
sodium thiosulphate using starch as an indicator. The reactions involved in the process
are given below.
Question 7.20:
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23. Class XII
Chapter 7 – The p Block Elements
Chemistry
What happens when sulphur dioxide is passed through an aqueous solution of Fe(III)
salt?
Answer
SO2 acts as a reducing agent when passed through an aqueous solution containing
Fe(III) salt. It reduces Fe(III) to Fe(II) i.e., ferric ions to ferrous ions.
Question 7.21:
Comment on the nature of two S−O bonds formed in SO2 molecule. Are the two S−O
bonds in this molecule equal?
Answer
The electronic configuration of S is 1s2 2s2 2p6 3s2 3p4.
During the formation of SO2, one electron from 3p orbital goes to the 3d orbital and S
undergoes sp2 hybridization. Two of these orbitals form sigma bonds with two oxygen
atoms and the third contains a lone pair. p-orbital and d-orbital contain an unpaired
electron each. One of these electrons forms pπ- pπ bond with one oxygen atom and the
other forms pπ- dπ bond with the other molecule. This is the reason SO2 has a bent
structure. Also, it is a resonance hybrid of structures I and II.
Both S−O bonds are equal in length (143 pm) and have a multiple bond character.
Question 7.22:
How is the presence of SO2 detected?
Answer
SO2 is a colourless and pungent smelling gas.
It can be detected with the help of potassium permanganate solution. When SO2 is
passed through an acidified potassium permanganate solution, it decolonizes the solution
as it reduces
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24. Class XII
Chapter 7 – The p Block Elements
Chemistry
Question 7.23:
Mention three areas in which H2SO4 plays an important role.
Answer
Sulphuric acid is an important industrial chemical and is used for a lot of purposes. Some
important uses of sulphuric acid are given below.
(i) It is used in fertilizer industry. It is used to make various fertilizers such as
ammonium sulphate and calcium super phosphate.
(ii) It is used in the manufacture of pigments, paints, and detergents.
(iii) It is used in the manufacture of storage batteries.
Question 7.24:
Write the conditions to maximize the yield of H2SO4 by Contact process.
Answer
Manufacture of sulphuric acid by Contact process involves three steps.
1. Burning of ores to form SO2
2. Conversion of SO2 to SO3 by the reaction of the former with O2
(V2O5 is used in this process as a catalyst.)
3. Absorption of SO3 in H2SO4 to give oleum (H2S2O7)
The key step in this process is the second step. In this step, two moles of gaseous
reactants combine to give one mole of gaseous product. Also, this reaction is
exothermic. Thus, in accordance with Le Chatelier’s principle, to obtain the maximum
amount of SO3 gas, temperature should be low and pressure should be high.
Question 7.25:
Why is
for H2SO4 in water?
Answer
It can be noticed that
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Chapter 7 – The p Block Elements
Chemistry
This is because a neutral H2SO4 has a much higher tendency to lose a proton than the
negatively charged
. Thus, the former is a much stronger acid than the latter.
Question 7.26:
Considering the parameters such as bond dissociation enthalpy, electron gain enthalpy
and hydration enthalpy, compare the oxidising power of F2 and Cl2.
Answer
Fluorine is a much stronger oxidizing agent than chlorine. The oxidizing power depends
on three factors.
1. Bond dissociation energy
2. Electron gain enthalpy
3. Hydration enthalpy
The electron gain enthalpy of chlorine is more negative than that of fluorine. However,
the bond dissociation energy of fluorine is much lesser than that of chlorine. Also,
because of its small size, the hydration energy of fluorine is much higher than that of
chlorine. Therefore, the latter two factors more than compensate for the less negative
electron gain enthalpy of fluorine. Thus, fluorine is a much stronger oxidizing agent than
chlorine.
Question 7.27:
Give two examples to show the anomalous behaviour of fluorine.
Answer
Anomalous behaviour of fluorine
(i) It forms only one oxoacid as compared to other halogens that form a number of
oxoacids.
(ii) Ionisation enthalpy, electronegativity, and electrode potential of fluorine are much
higher than expected.
Question 7.28:
Sea is the greatest source of some halogens. Comment.
Answer
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26. Class XII
Chapter 7 – The p Block Elements
Chemistry
Sea water contains chlorides, bromides, and iodides of Na, K, Mg, and Ca. However, it
primarily contains NaCl. The deposits of dried up sea beds contain sodium chloride and
carnallite, KCl.MgCl2.6H2O. Marine life also contains iodine in their systems. For example,
sea weeds contain upto 0.5% iodine as sodium iodide. Thus, sea is the greatest source
of halogens.
Question 7.29:
Give the reason for bleaching action of Cl2.
Answer
When chlorine reacts with water, it produces nascent oxygen. This nascent oxygen then
combines with the coloured substances present in the organic matter to oxide them into
colourless substances.
Coloured substances + [O] → Oxidized colourless substance
Question 7.30:
Name two poisonous gases which can be prepared from chlorine gas.
Answer
Two poisonous gases that can be prepared from chlorine gas are
(i) Phosgene (COCl2)
(ii) Mustard gas (ClCH2CH2SCH2CH2Cl)
Question 7.31:
Why is ICl more reactive than I2?
Answer
ICl is more reactive than I2 because I−Cl bond in ICl is weaker than I−I bond in I2.
Question 7.32:
Why is helium used in diving apparatus?
Answer
Air contains a large amount of nitrogen and the solubility of gases in liquids increases
with increase in pressure. When sea divers dive deep into the sea, large amount of
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27. Class XII
Chapter 7 – The p Block Elements
Chemistry
nitrogen dissolves in their blood. When they come back to the surface, solubility of
nitrogen decreases and it separates from the blood and forms small air bubbles. This
leads to a dangerous medical condition called bends. Therefore, air in oxygen cylinders
used for diving is diluted with helium gas. This is done as He is sparingly less soluble in
blood.
Question 7.33:
Balance the following equation: XeF6 + H2O → XeO2F2 + HF
Answer
Balanced equation
XeF6 + 2 H2O → XeO2F2 + 4 HF
Question 7.34:
Why has it been difficult to study the chemistry of radon?
Answer
It is difficult to study the chemistry of radon because it is a radioactive substance having
a half-life of only 3.82 days. Also, compounds of radon such as RnF2 have not been
isolated. They have only been identified.
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