#### 11th Standard Chemistry Basic Concepts of Chemistry & Chemical Calculations English Medium Free Online Test 1 Mark Questions with Answer Key 2020-20

11th Standard

Reg.No. :
•
•
•
•
•
•

Chemistry

Time : 00:20:00 Hrs
Total Marks : 20

20 x 1 = 20
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. Carbon forms two oxides, namely carbon monoxide and carbon dioxide. The equivalent mass of which element remains constant?

(a)

Carbon

(b)

Oxygen

(c)

Both carbon and oxygen

(d)

Neither carbon nor oxygen

3. 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

4. Fe2 + $\longrightarrow$ Fe3+ + e- is a ________ reaction.

(a)

redox

(b)

reduction

(c)

oxidation

(d)

decomposition

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. 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)

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

7. Consider the following statements :
(i) Oxidation number of He = zero
(ii) Increase in oxidation number results in reduction.
(iii) The substance undergoing the increase in oxidation number is reducing agent.
Which among the above statement(s) is/are correct?

(a)

only (i)

(b)

(ii) and (iii)

(c)

(i) and (iii)

(d)

only (ii)

8. 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)

9. 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

10. Which of the following compound(s) has /have a percentage of carbon same as that in ethylene (C2H4)

(a)

propene

(b)

ethyne

(c)

benzene

(d)

ethane

11. Maximum oxidation state is present in the central metal atom of which compound

(a)

CrO2Cl2

(b)

MnO2

(c)

[Fe(CN)6]3-

(d)

MnO

12. 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

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

(a)

Solids

(b)

Liquid

(c)

Gases

(d)

None of these

14. Which form of based on physical characteristics possess neither definite volume nor definite shape?

(a)

Solids

(b)

Liquids

(c)

Gases

(d)

Both (a) and (b)

15. 12 g of carbon-12 contains_____carbon atoms

(a)

6.022 x 1023

(b)

6

(c)

12

(d)

12.022 x 10-23 kg

16. The volume occupied by any gas at S.T.P. is_____

(a)

22.4litres

(b)

2.24litres

(c)

224 litres

(d)

0.224 litres

17. Unit of Avogadro's number is

(a)

mol

(b)

g

(c)

mol -1

(d)

No unit

18. One 'U' stands for the mass of

(a)

An atom of carbon-12

(b)

1/12th of the carbon-12

(c)

1/12th of a hydrogen atom

(d)

One atom of any of the element

19. In the reaction to NH3 + H2$\longrightarrow$ ${ NH }_{ 4 }^{ + }+O\overline { H }$, NH3 is acidic in. the reason for its acidic is_____

(a)

Acceptance of one H+from water

(b)

A release of one OH-ion

(c)

Due to the nitrogen atom

(d)

All the above

20. Assertion: The atomic masses of most of the elements. are in the fraction.
Reason:  The atomic mass represents the ratio of the average mass of the atom to one avogram.

(a)

Both assertion and reason are correct and the reason is the correct explanation for assertion

(b)

Both assertion and reason are correct but the reason is not the correct explanation for an assertion

(c)

Assertion is true but reason are false

(d)

Both assertion and reason are false