This document contains questions for a chemistry exam. It states that questions 1-10 are worth 1 mark each, questions 11-20 are worth 2 marks each, and question 21 is worth 5 marks. The questions cover various topics in chemistry including acids and bases, oxidation and reduction reactions, properties of elements and compounds, and preparation of chemicals.

1. QN 1 to 10 has 1-marks, QN 11 to 20 has 2-MARKS and QN 21 has 5-MARKS
1. What is the basicity of H3PO4?
2. What happens when H3PO3 is heated?
3. Write the order of thermal stability of the hydrides of Group 16
elements.
4. What do you meant by transition elements?
5. Name a transition element which does not exhibit variable
oxidation states.
6. How do you account for the reducing behaviour of H3PO2 on the
basis of its structure? Give one example.
7. H2S is less acidic than H2Te. Why?
8. List the important sources of sulphur.
9. Why is H2O a liquid and H2S a gas?
10. Which of the following does not react with oxygen directly?
Zn, Ti, Pt, Fe
11. Complete the following reactions:
(i) C2H4 + O2 → (ii) 4Al + 3 O2 →
12. Why does O3 act as a powerful oxidising agent?
13. What happens when sulphur dioxide is passed through an
aqueous solution of Fe(III) salt?
14. Mention three areas in which H2SO4 plays an important role.
15. On what ground can you say that scandium (Z = 21) is a transition
element but zinc (Z = 30) is not?
16. How can you prepare Cl2 from HCl and HCl from Cl2? Write
reactions only.
17. What are the oxidation states of phosphorus in the following
(i) H3PO3 (ii) PCl3 (iii) Ca3P2 (iv) Na3PO4 (v) POF3?
18. Write balanced equations for the following
(a) NaCl is heated with sulphuric acid in the presence of MnO2.
(b)Chlorine gas is passed into a solution of NaI in water.
19. Give the formula and describe the structure of a noble gas species
which is isostructural with
(i)ICl4
–
(ii) IBr2
–
(iii) BrO3
–
20. Why is Cr2+
reducing and Mn3+
oxidising when both have d4
configuration.
21. Indicate the steps in the preparation of: K2Cr2O7 from chromite
ore. How does the acidified dichromate solution react with
(i) iodide (ii) iron (II) solution and (iii) H2S
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QN 1 to 10 has 1-marks, QN 11 to 20 has 2-MARKS and QN 21 has 5-MARKS
22. Write the structure of S8 and S6.
23. Name two poisonous gases which can be prepared from chlorine
gas.
24. Why is ICl more reactive than I2?
25. Calculate the ‘spin only’ magnetic moment of M2+
(aq) ion (Z =
27).
26. Why is the highest oxidation state of a metal exhibited in its
oxide or fluoride only?
27. Noble gases have very low boiling points. Why?
28. Does the hydrolysis of XeF6 lead to a redox reaction?
29. Why has it been difficult to study the chemistry of radon?
30. Give the disproportionation reaction of H3PO3.
31. Why do the transition elements exhibit higher enthalpies of
atomization?
32. In the series Sc (Z = 21) to Zn (Z = 30), the enthalpy of atomization
of zinc is the lowest, i.e., 126 kJ mol–1
. Why?
33. Silver atom has completely filled d orbitals (4d10
) in its ground
state. How can you say that it is a transition element?
34. Can PCl5 act as an oxidising as well as a reducing agent? Justify
35. What is meant by ‘disproportionation’ of an oxidation state? Give
an example.
36. Write the conditions to maximise the yield of H2SO4 by Contact
process.
37. Write the balanced chemical equation for the reaction of Cl2 with
hot and concentrated NaOH. Is this reaction a disproportionation
reaction? Justify.
38. Give the reason for bleaching action of Cl2
39. Why are the elements of Group 18 known as noble gases?
40. Which is a stronger reducing agent Cr2+
or Fe2+
and why?
41. Predict which of the following will be colored in aqueous
solution?
Ti3+
, V3+
, Cu+
, Sc3+
, Mn2+
, Fe3+
and Co2+
Give reasons for each.
42. Describe the preparation of potassium permanganate. How does
the acidified permanganate solution react with
(i) iron (II) ions (ii) SO2 and (iii) oxalic acid?
Write the ionic equations for the reactions.
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