Exams

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PLEASE ENSURE YOU ARE SITTING FOR THE RIGHT EXAMINATION.
STUDENT’S NAME ADM NO. STREAM DATE
YEAR 10 MID OF TERM ONE EXAMINATION ACADEMIC
BIOLOGY - TIME: 1.30 HOURS.
INSTRUCTIONS. DIAGNOSTIC TABLE
 Fill in the boxes at the top of this page with your name,
Admission number and stream.
 Answer all questions.
 Read the questions carefully to make sure you know
What you are being asked to do.
 Underline or highlight any key words to help focus your answer.
 Remember that TALKING IS NOT ALLOWED
at any time in the exam room.
 All your answers should be WRITTEN WITH A PEN
 Keep your eyes on your own paper, remember copying is
CHEATING.
INFORMATION.
 The total marks for this paper are 70 MARKS.
 The marks for each question are shown in brackets.
QN MARKS
TOTAL
STUDENT MARKS (%)

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1. The diagram shows the electronic configurations of six different atoms.
A B C D E F
(a) You may use the Periodic Table on page 2 to help you answer this question.Answer
each part by writing one of the letters A, B, C, D, E or F in the box provided.
You may use each letter once, more than once or not at all.
Give the letter that represents an atom
(6)
(i) of a noble gas
(ii) that contains three protons
(iii) of phosphorus
(iv) of an element in Group 4 of the Periodic Table
(v) of an element in Period 3 of the Periodic Table
(vi) with a full outer shell of electrons
(b) Atoms of A and D combine to form a compound containing covalent bonds.
(i) Complete the sentence to describe a covalent bond.
(2)
A covalent bond is the electrostatic attraction between a pair of ........................................................................
and the ........................................................................ of two atoms.

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(b) Element X has three isotopes.
The table gives the mass number of each isotope and its percentage abundance in a
sample of element X.
Mass number Percentage abundance (%)
35 68.0
25 20.0
26 12.0
Calculate the relative atomic mass (Ar) of element X.
Give your answer to one decimal place.
(3)
2. The equation for the reaction between silicon dioxide and calcium oxide toform slag is
SiO2(s) + CaO(s) → CaSiO3(I)
a) What type of reaction is this?
(1)
A combustion
B decomposition
C neutralisation
D redox

4. b) One problem with using iron is rusting.
(ii) Name the two substances that must be present for iron to rust.
(2)
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(ii) One method of preventing iron from rusting is to paint it.
State how this method of rust prevention works.
(1)
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(e) Iron can also be protected from rusting by coating it with zinc.
(i) Give the name of this type of protection.
(1)
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5. 3. An atom of magnesium can be represented by the symbol
Use numbers to complete these statements about this atom. ( 3 marks)
(i) The atomic number of this atom is................................
(ii) The mass number of this atom is................................
(iii) The electronic configuration of this atom is................................
4. Name the gas being described in each of the following cases
(5 marks)
i. A green gas that bleaches damp litmus paper
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ii. A gas that dissolves readily in water to produce a solution with a pH of about 11
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iii. A gas that produces a white precipitate with lime water
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iv. A gas that pops when a lighted splint is placed on it
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v. A gas that relights a glowing splint
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6. 5. Rock salt is a mixture of salt and sand. Crystals of pure salt can be obtained from rock salt by
using the method below.
Use words from the box to complete the sentences.
You may use each word once, more than once or not at all.
(5)
crystals dissolve evaporate filter solution solvent

Grind the rock salt into a fine powder.
Add the powder to hot water and stir to
............................................................................. the salt.
Filter the mixture. The salt
............................................................................. passes through the filter
paper leaving behind the sand.
Boil the filtrate to ............................................................................. some
of the water.
Leave the saturated solution to cool so that
............................................................................. of salt form.
Finally, ............................................................................. the cold
mixture to separate the crystals from the remaining solution.

7. 6. Two compounds of barium are barium sulfide and barium chloride.
The sodium chloride solution is electrolysed in the apparatus shown in Figure 8.
Figure 8
(i) State why sodium chloride solution, rather than solid sodium chloride, must be used in this
experiment. ( 1
marks)
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(ii) The formulae of the ions present in the sodium chloride solution are
Circle the ions that would be attracted to the anode. ( 1 mark)
(iii) Molten lead bromide can be electrolysed to form molten lead and bromine gas.
Explain how a student could modify the apparatus shown in Figure 8 to carry out this electrolysis.
(2 marks)
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iv) Write the half equation at the cathode (1 mark)
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8. iv) Define the term reduction and oxidation in terms of electrons (2 marks)
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v) Define the term cathode and anode as used in electrolysis (2 marks)
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7. The diagram shows how the electrons are arranged in an atom of oxygen.
Oxygen atoms form both covalent and ionic bonds.
(a) Water is formed when two atoms of hydrogen combine with one atom of oxygen.
(i) Draw a dot and cross diagram of a molecule of water. You need only show the electrons in
the outer shells.
(2)

9. (ii) Explain how the covalent bonds in the water molecule hold the hydrogen and oxygen
atoms together.
(2)
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10. 10
(b) The electronic configuration of a sodium atom is 2.8.1
Sodium oxide, Na2O, is an ionic compound formed when sodium reacts with oxygen.
(i) Describe, in terms of electrons, what happens when sodium oxide is formed in this reaction.
(3)
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(c) Explain why water has a much lower melting point than sodium oxide.
(2)
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8. Use the Periodic Table on page 2 to help you answer this question.
Give the name or symbol of
(a) the element in group 3 and period 4.
(1)
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(b) an element in period 3 that is a good conductor of electricity.
(1)
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11. 11
(c) the element in group 7 that is the most reactive.
(1)
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(d) the element in group 5 that is present in a molecule of ammonia.
(1)
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(e) an element with an atom containing 8 electrons in its outer shell.
(1)
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9. This question is about hydrogen (H2) and water.
(a) Hydrogen is a gas at room temperature. It exists as simple molecules.
(i) Draw a dot and cross diagram to show the arrangement of the electrons in a
hydrogen molecule.(2)
(ii) Explain why hydrogen has a very low boiling point.
(2)
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12. 12
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(b) The symbols for the three isotopes of hydrogen are
1H 2H 3H
(i) State what is meant by the term isotopes.
(2)
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(ii) Complete the table to show the number of protons, neutrons and electrons in each of
the three isotopes of hydrogen.
(3)
Isotope
1H 2H 3H
number of protons
number of neutrons
number of electrons
(c) When hydrogen burns in oxygen, heat energy is transferred to the surroundings.
(i) State the name given to a reaction in which heat energy is transferred to the
surroundings.
(1)
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(ii) Write a chemical equation to represent the reaction that takes place when hydrogen
burns in oxygen.
(2)
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13. 13
(iii) Describe a chemical test to show that the product is water.
(2)
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(iv) Describe a physical test to show that the product is pure water.
(2)
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