#### 12th Standard Chemistry English Medium P - Block Elements - II Reduced Syllabus Important Questions 2021

12th Standard

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Chemistry

Time : 01:00:00 Hrs
Total Marks : 100

Multiple Choice Questions

15 x 1 = 15
1. In the brown ring test, brown colour of the ring is due to

(a)

a mixture of No and NO2

(b)

Nitroso ferrous sulphate

(c)

Ferrous nitrate

(d)

Ferric nitra

2. On hydrolysis, PCl3 gives

(a)

H3PO3

(b)

PH3

(c)

H3PO4

(d)

POCl3

3. Assertion : bond dissociation energy of fluorine is greater than chlorine gas
Reason: chlorine has more electronic repulsion than fluorine.
Codes:
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion
(c) Assertion is true but reason is false
(d) Both assertion and reason are false

(a)

Both assertion and reason are true and reason is the correct explanation of assertion.

(b)

Both assertion and reason are true but reason is not the correct explanation of assertion

(c)

Assertion is true but reason is false

(d)

Both assertion and reason are false

4. Which one of the following compounds is not formed?

(a)

XeOF4

(b)

XeO3

(c)

XeF2

(d)

NeF2

5. XeF6 on complete hydrolysis produces

(a)

XeOF4

(b)

XeO2F2

(c)

XeO3

(d)

XeO2

6. Among the following the correct order of acidity is

(a)

HClO2 < HClO < HClO3 < HClO4

(b)

HClO4 < HClO2 < HClO < HClO3

(c)

HClO3 < HClO4 < HClO2 < HClO

(d)

HClO < HClO2 < HClO3 < HClO4

7. When copper is heated with conc HNO3 it produces

(a)

Cu(NO3)2 , NO and NO2

(b)

Cu(NO3)2 and N2O

(c)

Cu(NO3)2 and NO2

(d)

Cu(NO3)2 and NO

8. Which of the following halides of group 15 is not hydrolysed?

(a)

NF3

(b)

PF3

(c)

NI3

(d)

Both (a) and (b)

9. Which is dibasic?

(a)

Orthophosphoric acid

(b)

Pyrophosphoric acid

(c)

Orthophosphorus acid

(d)

Hypophosphorus acid

10. S-S bond is present in

(a)

H2S2O7.

(b)

H2SO5

(c)

H2S2O6

(d)

H2S2O6

11. Least volatile hydrogen halide is

(a)

HF

(b)

HCI

(c)

HBr

(d)

HI

12. Orthophosphorus acid on heating gives________

(a)

Hypophosphorus

(b)

Orthophosphoric acid

(c)

Phosphine gas

(d)

both (b) and (c)

13. The incorrect statement regarding structure of ozone is______

(a)

Bond angle is less than 120°

(b)

It is linear

(c)

The two oxygen-oxygen bond length in ozone are identical

(d)

Both (b) and (c).

14. Strong reducing behaviour of H3PO2 is due to______

(a)

High oxidation state of phosphorus

(b)

High electro gain enthalpy of phosphorus

(c)

Presence of two-OH groups and one P-H bond

(d)

Presence of one-OH groups and two P-H bonds

15. Helium is used in balloons in the place of, hydrogen because it is________

(a)

incombustible

(b)

(c)

lighter than hydrogen

(d)

both (a) and(c)

16. 2 Marks

10 x 2 = 20
17. What is inert pair effect?

18. Chalcogens belongs to p-block. Give reason.

19. What are interhalogen compounds? Give examples.

20. Give two uses of nitric acid

21. Elements of group 16 show lower value of first ionization enthalpy compared to group 15, why?

22. (i) Give correct order of boiling point of hydride of group 17.
(ii) Fluorine exhibits only -1 oxidation state whereas other halogens show +1, +3, +5 and +7 oxidation state also Explain.

23. Why does ozone act as a powerful oxidising agent?

24. Acidic character increases from HF to HI. I State whether the above statement is True or false and give reason for your answer.

25. Account for the following:
(i) O-O bond lengths in ozone molecule are identical.
(ii) Most of the reactions in fluorine are exothermic.

26. Why hydrides of oxygen is a liquid whereas hydride of sulphur is a gas?

27. 3 Marks

10 x 3 = 30
28. How will you prepare chlorine in the laboratory?

29. Give the uses of sulphuric acid.

30. Give a reason to support that sulphuric acid is a dehydrating agent.

31. Give the uses of argon.

32. Explain the structure of ammonia

33. Give a test for sulphate?

34. Discuss the anomalous nature of fluorine.

35. Write the order of thermal stability of the hydrides of group 16 elements.

36. Explain why the stability of oxaacids of chlorine increases in the order given below?
HCIO < HCIOz < HCIO3 < HCIO4

37. Predict the product
(i) PCI5+ C2H5OH $\longrightarrow$?
(ii) P4+ SO2Cl2 $\longrightarrow$ ?
(iii) POCl3 + H2O $\longrightarrow$ ?
(iv) HBr + PH3$\longrightarrow$ ? :,
(v) PCl3+ H2O$\longrightarrow$ ?

38. 5 Marks

7 x 5 = 35
39. What happens when PCl5 is heated?

40. Suggest a reason why HF is a weak acid, whereas binary acids of the all other halogens are strong acids.

41. Give a detailed account of the interhalogen, compounds with special reference to the: compounds involving iodine. Draw their structures.

42. Give a detailed account on allotropes of sulphur.

43. Complete the following reactions
(i) KCIO3$\longrightarrow$?
(ii) ZnS + O2$\longrightarrow$ ?
(iii) Al2O3 + NaOH + H2O$\longrightarrow$ ?
(iv) NaOH + SO2$\longrightarrow$ ?
(v) KCI+ H2SO4 $\longrightarrow$ ?

44. How is sulphuric acid manufacture by contact process?

45. An element A occupies group number 15 and period number 3, reacts with chlorine to give compound B. The compound B on hydrolysis gives a dibasic acid C. The compound C on heating undergoes auto oxidation and reduction to give a tribasic acid D. Identify the elements A, compounds B, C and D. Write the reactions