Important Question paper

11th Standard

Reg.No. :
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Chemistry

Use Blue pen only
Time : 00:50:00 Hrs
Total Marks : 50

Part-A

15 x 1 = 15
1. The number of water molecules in a drop of water weighing 0.018 g is

(a)

6.022 x 1026

(b)

6.022 x1023

(c)

6.022 x 1020

(d)

9.9 x 1022

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. When 6.3g of sodium bicarbonate is added to 30g of the acetic acid solution, the residual solution is found to weigh 33g. The number of moles of carbon dioxide released in the reaction is

(a)

3

(b)

0.75

(c)

0.075

(d)

0.3

4. When 22.4 litres of H2(g) is mixed with 11.2 litres of Cl2(g), each at 273 K at 1 atm the moles of HCl (g), formed is equal to

(a)

2 moles of HCI (g)

(b)

0.5 moles of HCI (g)

(c)

1.5 moles of HCI (g)

(d)

1 moles of HCI (g)

5. The oxidation number of oxygen in O2 is _______________

(a)

0

(b)

+1

(c)

+2

(d)

-2

6. The oxidation number of hydrogen in LiH is _____________

(a)

+1

(b)

-1

(c)

+2

(d)

-2

7. Total number of electrons present in 1.7 g of ammonia is

(a)

6.022 x 1023

(b)

$\frac { 6.022\times { 10 }^{ 22 } }{ 1.7 } \quad$

(c)

$\frac { 6.022\times { 10 }^{ 24 } }{ 1.7 }$

(d)

$\frac { 6.022\times { 10 }^{ 23 } }{ 1.7 }$

8. The oxidation number of Cr in Cr2O72- __________ is

(a)

+6

(b)

-6

(c)

+7

(d)

-7

9. Identify disproportionation reaction

(a)

CH4 + 2O2 $\longrightarrow$ CO2+ 2H2O

(b)

CH4 + 4Cl2 $\longrightarrow$ CCl4 + 4HCI

(c)

2F2+ 2OH $\longrightarrow$ 2F-+ OF2+ H2O

(d)

2NO2 + 2OH- $\longrightarrow$ NO-2 + NO-3 + H2O

10. Which of the following statement(s) is/are not true about the following decomposition reaction.
2KClO3 $\longrightarrow$ 2KCl + 3O2
(i) Potassium is undergoing oxidation
(ii) Chlorine is undergoing oxidation
(iii) Oxygen is reduced
(iv) None of the species are undergoing oxidation and reduction.

(a)

only (iv)

(b)

(i) and (iv)

(c)

(iv) and (iii)

(d)

All of these

11. Match the list-I with list-II and select the correct answer using the code given below the lists.

 List-I List-II A Cr2O72- 1 +5 B MnO4- 2 +6 C VO3- 3 +3 D FeF63+ 4 +7
(a)
 A B C D 3 1 4 2
(b)
 A B C D 4 3 2 1
(c)
 A B C D 2 4 1 3
(d)
 A B C D 3 2 1 4
12. Two 22.4 litre containers A and B contains 8 g of O2 and 8 g of SO2 respectively at 273 K and 1 atm pressure, then

(a)

Number of molecules inA and B are same

(b)

Number of molecules in B is more than that in A.

(c)

The ratio between the number of molecules in A= to number of molecules in B is 2:1

(d)

Number of molecules in B is three times greater than the number of molecules in A

13. Consider the following statements
i) Matter possesses mass.
ii) 22-carat gold is a mixture.
iii) Dry ice is a compound.
Which of the following statement(s) given above is/ are correct?

(a)

1 & 3

(b)

Only 1

(c)

1 & 2

(d)

1,2, & 3

14. Identify the incorrect statement about a compound.

(a)

A molecule cannot be separated into its constituent elements by physical methods of separation

(b)

A molecule of a compound has atoms of different elements

(c)

A compound retains the physical properties of its constituent element

(d)

The ratio of atoms of different elements in a compound is fixed

15. The characteristic feature of orderly arrangement of molecules belongs to

(a)

Solids

(b)

Liquid

(c)

Gases

(d)

None of these

16. Part-B

10 x 2 = 20
17. The density of carbon dioxide is equal to 1.965 kgm-3 at 273 K and 1 atm pressure. calculate the molar mass of CO2

18. Which contains the greatest number of moles of oxygen atoms
i) 1 mol of ethanol
ii) 1 mol of formic acid
iii) 1 mol of H2O

19. Calculate the average atomic mass of naturally occurring magnesium using the following data

Isotope Istopic atomic mass Abundance(%)
Mg24 23.99 78.99
Mg26 24.99 10.00
Mg25 25.98 11.01
20. 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).

21. Balance the following equations by ion electron method -
i) ${ KMn }O_{ 4 }+{ SnCl }_{ 2 }+HCI\longrightarrow MnCI_{ 2 }+{ SnCI }_{ 4 }+{ H }_{ 2 }O+KCI$
ii) ${ C }_{ 2 }{ O }_{ 4 }^{ 2- }+{ Cr }_{ 2 }{ O }_{ 7 }^{ 2- }\longrightarrow { Cr }^{ 3+ }+{ CO }_{ 2 }$ (in acid medium)
iii) ${ Na }_{ 2 }{ S }_{ 2 }{ O }_{ 3 }+{ I }_{ 2 }\longrightarrow { Na }_{ 2 }{ S }_{ 4 }{ O }_{ 6 }+NaI$
iv) $Zn+{ NO }_{ 3 }^{ - }\longrightarrow { Zn }^{ 2+ }+No$

22. Balance the following equations by ion electron method - ${ C }_{ 2 }{ O }_{ 4 }^{ 2- }+{ Cr }_{ 2 }{ O }_{ 7 }^{ 2- }\longrightarrow { Cr }^{ 3+ }+{ CO }_{ 2 }$ (in acid medium)

23. Balance the following equations by ion electron method ${ Na }_{ 2 }{ S }_{ 2 }{ O }_{ 3 }+{ I }_{ 2 }\longrightarrow { Na }_{ 2 }{ S }_{ 4 }{ O }_{ 6 }+NaI$

24. Define orbital? what are the n and 1 values for 3px and 4dx2-y2 electron?

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

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

27. Part-C

5 x 3 = 15
28. One million silver atoms weigh 1.79 x 10-16 g. Calculate the atomic mass of silver.

29. How much mass (in gram units) is represented by the following?
0.2 mol of NH3

30. How much mass (in gram units) is represented by the following?
3.0 mol of CO2

31. How much mass (in gram units) is represented by the following?
5.14 mol of H5IO6

32. Calculate the Formula Weights of the following compounds.NO2