#### 11th Public Exam March 2019 Model Question

11th Standard

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Chemistry

Time : 02:30:00 Hrs
Total Marks : 70
15 x 1 = 15
1. The number of molecules in 40 g of sodium hydroxide is _______________

(a)

6.023 x 10-23

(b)

3.0115 x 1023

(c)

6.023 x 1023

(d)

2 x 6.023 x 1023

2. Two electrons occupying the same orbital are distinguished by

(a)

azimuthal quantum number

(b)

spin quantum number

(c)

magnetic quantum number

(d)

orbital quantum number

3. The oxidation state of alkali metal is _______

(a)

+2

(b)

+1

(c)

+3

(d)

0

4. Ionic hydrides are formed by

(a)

halogens

(b)

chalogens

(c)

inert gases

(d)

group one elements

5. Which is the correct sequence of solubility of  carbonates of alkaline earth metals?

(a)

BaCO3 > SrCO3 > CaCO3 > MgCO3

(b)

MgCO3 > CaCO3 > SrCO3 > BaCO3

(c)

CaCO3 > BaCO3 > SrCO3 > BaCO3

(d)

BaCO3 > CaCO3 > SrCO3 > MaCO3

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 work done by the liberated gas when 55.85 g of iron (molar mass 55.85 g mol-1) reacts with hydrochloric acid in an open beaker at 25°C

(a)

- 2.48 kJ

(b)

-2.22 kJ

(c)

+2.22 kJ

(d)

+ 2.48 kJ

8. The oxidation of S02 and 02 to S03 is an exothermic reaction. The yield of S03 will be maximum if

(a)

Temperature and pressure both are increased

(b)

Temperature decreased, pressure increased

(c)

Temperature increased, pressure constant

(d)

Temperature and pressure both decreased

9. Normality of 1.25M sulphuric acid is

(a)

1.25 N

(b)

3.75 N

(c)

2.5 N

(d)

2.25 N

10. Which among the following molecule obeys octet rule?

(a)

NO

(b)

NO2

(c)

N2O3

(d)

ClO2

11. A sample of 0.5g of an organic compound was treated according to Kjeldahl’s method. The ammonia evolved was absorbed in 50mL of 0.5M H2SO4. The remaining acid after neutralisation by ammonia consumed 80mL of 0.5 MNaOH, The percentage of nitrogen in the organic compound is.

(a)

14%

(b)

28%

(c)

42%

(d)

56%

12. Which of the following species is not electrophilic in nature?

(a)

Cl+

(b)

BH3

(c)

H3O+

(d)

+NO2

13. The number of axial hydrogen atoms in chair form of cyclohexane is

(a)

3

(b)

6

(c)

12

(d)

2

14. Hunsdiecker reaction is used to prepare alkyl chloride and alkyl bromide starting from

(a)

diazonium salt

(b)

silver salts of carboxylic acid

(c)

sodium salt of carboxylic acid

(d)

alcohol

15. Ozone depletion will cause

(a)

forest fires

(b)

eutrophication

(c)

bio magnification

(d)

global warming

16. 7 x 2 = 14
17. Define relative atomic mass

18. The stabilisation of a half filled d - orbital is more pronounced than that of the p-orbital why?

19. What are the anomalies of the long form of periodic table?

20. Give an expression for the rate of diffusion of a gas and to its molecular weight

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 does the effect of the process C2 $\rightarrow$ C2+ + e- affect the bond order?

23. Explain paper chromatography.

24. How does the addition reaction affect the hybridisation of the substrale? Give example.

25. Explain the mechanism of SN1 reaction by highlighting the stereochemistry behind it

26. 7 x 3 = 21
27. Calculate the amount of water produced by the combustion of 32 g of methane.

28. What are transfermium elements?

29. Complete the following chemical reactions and classify them in to (a) hydrolysis (b) redox (c) hydration reactions.
(1) KMnO4 + 3H2O2 ➝ 2MnO2+2KOH+2H2O+3O2
(2) CrCl3+H2O ➝
(3) CaO + H2O ➝

30. Which of the following gases would you expect to deviate from ideal behavior under conditions of low-temperature F2, CI2, or Br2? Explain.

31. Mention the condition for Adiabatic, isothermal, isobaric, isochoric and cyclic process.

32. The observed depression in freezing point of water for a particular solution is 0.093o C. Calculate the concentration of the solution in molality. Given that molal depression constant for water is 1.86 KKg mol-1.

33. Suggest and explain the method suitable to purify the organic compounds depending on their boiling points.

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

36. 5 x 5 = 25
1. Explain displacement reaction.

2. Explain the periodic trend of ionisation potential.

1. (a) How is H2O2 prepared?
(b) Explain about the structure of H2O2

2. Discus the similarities between beryllium and aluminium.

1. Calculate the total pressure in a mixture of 8 g of oxygen and 4 g of hydrogen confined in a vessel of 1 dm3 at 27° C. [R = 0.083 bar dm3 K-1 mol-1.]

2. List the characteristics of Gibbs free energy

1. The equilibrium constant at 298 K for a reaction is 100.
A + B $\rightleftharpoons$ C + D
If the initial concentration of all the four species is 1 M, the equilibrium concentration of D (in mol lit-1) will be

2. Write a note on principle involved in chromatography and explain thin layer chromatography.

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

2. Ethane burns completely in air to give CO2, while in a limited supply of air gives CO. The same gases are found in automobile exhaust. Both CO and CO2 are atmospheric pollutants
i) What is the danger associated with these gases
ii) How do the pollutants affect the human body?