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#### Quarterly Model Question Paper

11th Standard

Reg.No. :
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Chemistry

Time : 01:30:00 Hrs
Total Marks : 70
15 x 1 = 15
1. An element X has the following isotopic Composition 200X = 90%, 199X = 8% and 202X = 2% The Weighted average atomic mass of the element X is closet to

(a)

201 u

(b)

202 u

(c)

199 u

(d)

200 u

2. 1 g of an impure sample of magnesium carbonate (containing no thermally decomposable impurities) on complete thermal decomposition gave 0.44 g of carbon dioxide gas. The percentage of impurity in the sample is ______________

(a)

0%

(b)

4.4%

(c)

16%

(d)

8.4%

3. Hot concentrated sulphuric acid is a moderately strong oxidizing agent. Which of the following reactions does not show oxidising behaviour?

(a)

Cu + 2H2 SO4 $\longrightarrow$ CuSO4 +SO2 + 2H2O

(b)

C + 2H2 + SO4 $\longrightarrow$ CO2 + 2SO2 + 2H2O

(c)

BaCl2 + H2SO4 $\longrightarrow$ BaSO4 + 2HCl

(d)

None of the above

4. The oxidation number of oxygen in O2 is _______________

(a)

0

(b)

+1

(c)

+2

(d)

-2

5. Which one of the following represents 180g of water?

(a)

5 Moles of water

(b)

90 moles of water

(c)

$\frac { 6.022\times { 10 }^{ 23 } }{ 180 }$ molecules of water

(d)

6.022 x 1024molecules of water

6. 7.5 g of a gas occupies a volume of 5.6 litres at 0° C and 1 atm pressure. The gas is

(a)

NO

(b)

N2O

(c)

CO

(d)

CO2

7. The mass of a gas that occupies a volume of 612.5 ml at room temperature and pressure (250 c and 1 atm pressure) is 1.1g. The molar mass of the gas is

(a)

66.25 g mol-1

(b)

44 g mol-1

(c)

24.5 g mol-1

(d)

662.5 g mol-1

8. Which one of the following is used as a standard for atomic mass.

(a)

6C12

(b)

7C12

(c)

6C13

(d)

6C14

9. Assertion (A): In the reaction between potassium permanganate and potassium iodide, permanganate ions act as oxidising agent.
Reason (R): Oxidation state of manganese changes from +2 to +7 during the reaction.

(a)

Both A and R are true and R explains A

(b)

Both A and R are true but R does not explain A

(c)

A is true but R is false

(d)

Both A and R are false

10. Calculate the percentage of N in ammonia molecule.

(a)

121.42%

(b)

28.35%

(c)

82.35%

(d)

28.53%

11. How many moles of magnesium phosphate Mg3(PO4)2 Will Contain 0.25 moles of oxygen atoms?

(a)

0.02

(b)

3.125 x 10-2

(c)

1.25 x 10-2

(d)

2.5 x 10-2

12. The number of molecules in 16g of methane is:

(a)

3.023 x 1023

(b)

6.023 x 1023

(c)

16/6.023 x 1023

(d)

6.023/3 x 1023

13. The molar mass of Na2SO4 is.....

(a)

129

(b)

142

(c)

110

(d)

70

14. Which is the lightest among the following?

(a)

An atom of hydrogen

(b)

An electron

(c)

A neutron

(d)

A proton

15. The energy of electron in an atom is given by En =

(a)

$\frac { 4{ \pi }^{ 2 }{ me }^{ 4 } }{ { n }^{ 2 }h^{ 2 } }$

(b)

$\frac { 2{ \pi }^{ 2 }{ me }^{ 4 } }{ { n }^{ 2 }h^{ 2 } }$

(c)

$\frac { 2{ \pi }^{ 2 }{ me }^{ 4 } }{ { n }^{ 2 }h^{ 2 } }$

(d)

$\frac { 2{ \pi }{ me }^{ 4 } }{ { n }^{ 2 }h^{ 2 } }$

16. 6 x 2 = 12
17. What do you understand by the term oxidation number?

18. Energy of an electron in hydrogen atom in ground state is -13.6 eV. What is the energy of the electron in the second excited state?

19. At room temperature, Hydrogen reacts very slowly. Explain

20. Discuss the biological importance of sodium and potassium.

21. What is milk of lime? How CO2 reacts with it?

22. What is the usual definition of entropy? What is the unit of entropy?

23. 6 x 3 = 18
24. Categorise the redox reactions that occur in our daily life

25. Zn rod is immersed in CuSO4 solution. What will you observe after an hour? Explain you observation in terms of the redox reaction.

26. Calculate the empirical and molecular formula of a compound containing 76.6% carbon, 6.38 % hydrogen and rest oxygen its vapour density is 47

27. a) 0.456 g of a metal gives 0.606 g of its chloride. Calculate the equivalent mass of the metal.
b) Calculate the equivalent mass of potassium dichromate. The reduction half-reaction in acid medium is Cr2072- + 14H+ 6e- $\rightarrow$ 2Cr3++7H20

28. A sample of gas at 15°C at 1 atm. has a volume of 2.58 dm3. When the temperature is raised to 38°C at 1 atm does the volume of the gas increase? If so, calculate the final volume.

29. State the various statements of second law of thermodynamics.

30. 5 x 5 = 25
31. A Compound on analysis gave Na = 14.31% S = 9.97% H= 6.22% and 0= 69.5% calculate the molecular formula of the compound if all the hydrogen in the compound is present in combination with oxygen as a water of crystallization. (molecular mass of the compound is 322).

32. Balance the following equations by oxidation number method.
P + HNO3 ⟶ HPO3 + NO + H2O

33. What is screening effect? Briefly give the basis for pauling's scale of electronegativity.

34. Give the structural features of modern periodic law.

35. Explain whether a gas approaches on ideal behavior or deviates from ideal behaviour if
(a) it is compressed to a smaller volume at constant temperature.
(b) the temperature is raised at while keeping the volume constant
(c) more gas is introduced into the same volume and at the same temperature