9th class Chemistry, Chapter 10: Environmental Chemistry MCQs

1. Which gases are responsible for greenhouse effect?

1. (A) SO₂, NO₂
2. (B) NO₂, CO
3. (C) CO₂, CH₄ ✓
4. (D) O₂, N₂

2. Indicate the source of sulphur which is responsible for the presence of oxides of sulphur in the atmosphere.

1. (A) Decomposition of vegetation
2. (B) Waste gases from digestion of animals
3. (C) Photochemical smog
4. (D) Combustion of fossil fuels ✓

3. Concentration of which gas in the atmosphere is decreased by photosynthesis in plants?

1. (A) Oxygen
2. (B) Nitrogen
3. (C) Carbon dioxide ✓
4. (D) Water vapours

4. Which substance remains unaffected in the catalytic converter fixed in the exhaust of the automobiles?

1. (A) CO₂ ✓
2. (B) CO
3. (C) NO
4. (D) NO₂

5. People of which age groups are most affected by the air pollution?

1. (A) Young adults
2. (B) Middle age people
3. (C) Children
4. (D) Both children and aged people ✓

6. In which area there is a greater possibility of acid rain?

1. (A) Around village
2. (B) Around big cities
3. (C) Around industrial area ✓
4. (D) Around water bodies

7. Why is smog not felt in summer?

1. (A) Because fog is not present in summer ✓
2. (B) Because due to heat of the Earth the smoke rises up
3. (C) Because in summer smoke and fog cannot mix with each other
4. (D) Because less fossil fuels are burnt in summer

8. Which catalyst is used in the catalytic converter fixed in the exhaust systems of automobiles?

1. (A) Ni
2. (B) Cu
3. (C) Pt, Pd and Rh ✓
4. (D) CaO

9. Which components are essential for the formation of photochemical smog?

1. (A) CO, NO₂, CO₂
2. (B) NO₂, volatile organic compounds, sunlight ✓
3. (C) CO₂, NO₂, sunlight
4. (D) Volatile organic compounds, NO₂, CO

10. Which gases contribute towards the formation of acid rain?

1. (A) Oxides of carbon
2. (B) Oxides of sulphur
3. (C) Oxides of nitrogen
4. (D) Both the oxides of nitrogen and sulfur ✓

11. The branch of chemistry which studies chemicals and pollutants in the environment is:

1. (A) Geochemistry
2. (B) Biochemistry
3. (C) Environmental chemistry ✓
4. (D) Analytical chemistry

12. Which of the following is a fossil fuel?

1. (A) Wind
2. (B) Biomass
3. (C) Solar energy
4. (D) Natural gas ✓

13. The percentage of nitrogen in air by volume is:

1. (A) 78.0% ✓
2. (B) 21.0%
3. (C) 0.934%
4. (D) 0.04%

14. The percentage of oxygen in air by volume is:

1. (A) 21.0% ✓
2. (B) 78.0%
3. (C) 1.0%
4. (D) 0.04%

15. The percentage of carbon dioxide in air is:

1. (A) 1.0%
2. (B) 4.0%
3. (C) 0.04% ✓
4. (D) 0.934%

16. The amount of water vapours in air depends upon the:

1. (A) Oxygen
2. (B) Nitrogen
3. (C) Humidity ✓
4. (D) Pressure

17. The concentration of a pollutant is expressed in:

1. (A) Parts per million (ppm) ✓
2. (B) g/cm³
3. (C) kJ mol⁻¹
4. (D) pm

18. Seven types of harmful substances account for more than ____ of air pollution.

1. (A) 70%
2. (B) 25%
3. (C) 90% ✓
4. (D) 50%

19. NO and NO₂ are collectively called:

1. (A) VOCs
2. (B) Particulates
3. (C) NOₓ ✓
4. (D) SOₓ

20. Methane is released into air by:

1. (A) Lightning
2. (B) Photosynthesis
3. (C) Decomposition of vegetation ✓
4. (D) Volcanic eruption only