#### 11th Half Yearly Important Questions

11th Standard

Reg.No. :
•
•
•
•
•
•

Chemistry

Time : 02:30:00 Hrs
Total Marks : 70
I. Choose the best suitable answer:
15 x 1 = 15
1. Identify the correct statement(s) with respect to the following reaction :
Zn + 2HCl $\longrightarrow$ ZnCl2 + H2
(i) Zinc is acting as an oxidant
(ii) Chlorine is acting as a reductant
(iii) Hydrogen is not acting as an oxidant
(iv) Zn is acting as a reductant

(a)

only (ii)

(b)

only (iv)

(c)

both (ii) and (iii)

(d)

both (ii) and (i)

2. What is the maximum numbers of electrons that can be associated with the following set of quantum numbers? n = 3, I = 1 and m =-1

(a)

4

(b)

6

(c)

2

(d)

= 10

3. Match the list-I and list-II using the code given below the list

 List-I List-II A.Law of triads 1.Chancourtois B.Law of octaves 2.Henry Moseley C.First periodic law 3.Newland D.Modem periodic law 4.Johann Dobereiner
(a)
 A B C D 4 3 1 2
(b)
 A B C D 3 4 2 1
(c)
 A B C D 1 3 4 2
(d)
 A B C D 2 3 1 4
4. Which of the following statements about hydrogen is incorrect?

(a)

Hydrogen ion, H3O+ exists freely in solution.

(b)

Dihydrogen acts as a reducing agent.

(c)

Hydrogen has three isotopes of which tritium is the most common.

(d)

Hydrogen never acts. as cation in ionic salts

5. Assertion : BeSO4 is soluble in water while BaSO4 is not
Reason : Hydration energy decreases down the group from Be to Ba and lattice energy remains almost constant.

(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.

6. The value of the gas constant R is

(a)

0.082 dm2 atm.

(b)

0.987 cal mol-1K-1

(c)

8.3 J mol-1 K-1

(d)

8 erg mol-1 K-1

7. The bond dissociation energy of methane and ethane are 360 kJ mol-1 and 620 kJ mol-1 respectively. Then, the bond dissociation energy of C-C bond is

(a)

170 kJ mol-1

(b)

50 kJ mol-1

(c)

80 kJ mol-1

(d)

220 kJ mol-1

8. Two moles of N2 and two moles of H2 are taken in a closed vessel of 5 litre capacity and suitable conditions are provided for the reaction. When the equilibrium is reached, it is found that a half mole of N2 is used up. The equilibrium concentration of NH3 is

(a)

0.2

(b)

0.4

(c)

0.3.

(d)

0.1

9. Stomach acid, a dilute solution of HCl can be neutralised by reaction with Aluminium hydroxide
Al (OH)3 + 3HCl (aq) → AlCl3 + 3 H2O
How many millilitres of 0.1 M Al(OH)3 solution are needed to neutralise 21 mL of 0.1 M HCl?

(a)

14 mL

(b)

7 mL

(c)

21 mL

(d)

none of these

10. The formula of the compound is A2B3. The number of electrons in the outermost orbits of A and B respectively are,

(a)

3 and 6

(b)

3 and 2

(c)

2 and 3

(d)

5 and 2

11. The IUPAC name of the compound CH– CH = CH – C ≡ CH is

(a)

Pent - 4 - yn-2-ene

(b)

Pent -3-en-l-yne

(c)

pent – 2– en – 4 – yne

(d)

Pent – 1 – yn –3 –ene

12. Which of the following carbocation will be most stable?

(a)

Ph3C-+

(b)

${ C }{ H }_{ 3 }-\overset { + }{ C } { H }_{ 2 }$

(c)

$\left( { CH }_{ 3 } \right) _{ 2 }-\overset { + }{ C } { H }$

(d)

$CH_{ 2 }=CH-\overset { + }{ C } { { H }_{ 2 } }$

13. Which of the following has maximum angle strain?

(a)

(b)

(c)

(d)

14. ${ CH }_{ 3 }-{ CH }_{ 3 }-Br\overset { KCN }{ \longrightarrow } X\overset { dil.HCl }{ \underset { \triangle }{ \longrightarrow } } Z$ Z is

(a)

CH3CH2COOH

(b)

CH3COOH

(c)

CH3COCI

(d)

CH3CONH2

15. Identify the wrong statement in the following

(a)

The clean water would have a BOD value of more than 5 ppm

(b)

Greenhouse effect is also called as Global warming

(c)

Minute solid particles in air is known as particulate pollutants

(d)

Biosphere is the protective blanket of gases surrounding the earth

16. II. Answer any six questions. Q.No 18 is compulsory
6 x 2 = 12
17. If 10 volumes of H2 gas react with 5 volumes of O2 gas, how many volumes of water vapour would be produced?

18. How many orbitals are possible for n =4?

19. On the basis of quantum numbers, justify that the sixth period of the periodic table should have 32 elements.

20. Deep sea divers ascend slowly and breath continuously by time they reach the surface. Give reason.

21. Consider the following equilibrium reactions
and relate their equilibrium, constants
i) N2 + O2 ⇌ 2NO ; K1
ii) 2NO + O2 ⇌ 2NO2 ; K2
iii) N2 + 2O2 ⇌ 2NO2 ; K3

22. How may lone pairs and bond pairs are present in ${ SO }_{ 4 }^{ 2- }$ and H3O+?

23. What is meant by a functional group? Identify the functional group in the following compounds.
(a) acetaldehyde
(b) oxalic acid
(c) di methyl ether
(d) methylamine

24. Why is benzylic free radical more stable than allylic free radical?

25. Compare SN1 and SN2 reaction mechanisms.

26. III. Answer any six questions. Q.No 27 is compulsory

6 x 3 = 18
27. How much volume of chlorine is required to form 11.2 L of HCI at 273 K and 1 atm pressure?

28. Why there is a need for classification of elements?

29. Hydrogen peroxide can function as an oxidising agent as well as reducing agent. substantiate this statement with suitable examples.

30. Suggest why there is no hydrogen (H2) in our atmosphere. Why does the moon have no atmosphere?

31. Give reason for the following statements. U is an extensive property

32. Vapour pressure of a pure liquid A is 10.0 torr at 27°C. The vapour pressure is lowered to 9.0 torr on dissolving one gram of B in 20 g of A. If the molar mass of A is 200 then calculate the molar mass of B.

33. Complete the following reactions:
(i) $({ CH }_{ 3 }COO)_{ 2 }pb+Na_{ 2 }S\rightarrow ?$
(ii) ${ Na }_{ 2 }[(Fe(CN)_{ 5 }NO]+{ Na }_{ 2 }S\rightarrow ?$
(iii) $NaCNS+FeCI_{ 3 }\rightarrow ?$
(iv) $Na_{ 2 }S+AgNO_{ 3 }\rightarrow ?$
(v) $BaCI_{ 2 }+{ Na }_{ 2 }{ SO }_{ 4 }\rightarrow ?$
(vi) ${ Na }_{ 4 }[Fe(CN)_{ 6 }]+{ FeCI }_{ 3 }\rightarrow ?$

34. Explain the isomerism exhibited by alkenes.

35. Dissolved oxygen in water is responsible for aquatic life. What processes are responsible for the reduction in dissolved oxygen in water?

36. IV. Answer all the questions in detail:
5 x 5 = 25
1. Write the steps to be followed while balancing redox equation by oxidation number method.

2. By using paulings method calculate the ionic radii of K+ and CI- ions in the potassium chloride crystal. Given that dk+-cl-=3.14 Å.

1. Why does hydrogen occur in a diatomic form rather than in a monoatomic form under normal conditions?

2. Alkaline earth metal (A), belongs to 3rd period reacts with oxygen and nitrogen to form compound (B) and (C) respectively. It undergo metal displacement reaction with AgNO3 solution to form compound (D).

1. When the temperature of a gas increases from 0°C the volume of the gas increases by a factor of 1.25.what is the final temperature?

2. List the characteristics of internal energy.

1. The equilibrium constant KP for the reaction
N2(g) + 3H2(g) ⇌ 2NH3(g) is 8.19 × 102 at 298 K and 4.6 × 10–1 at 498 K. Calculate ΔHo for the reaction

2. Describe the estimation of the amount of nitrogen present in an organic compound by Dumas method.

1. Give a detailed account on the different mechanisms followed in elimination reaction.

2. What are particulate pollutants? Explain any three.