Chemistry 9th Chap 11 : Topic 2 - Maryam Publications

Chemistry Chapter 11 : Topic 2

Sources of Air Pollutants

1 / 20

Which of the following is the major source of carbon dioxide in the atmosphere?

A) Decomposition of plants in marshes

B) Incomplete combustion of hydrocarbons in engines

C) Reaction of nitrogen and oxygen in air

D) Complete combustion of carbon-containing fuels such as coal and petrol

2 / 20

Carbon monoxide is mainly produced when:

A) Carbon dioxide reacts with oxygen

B) Fuel burns completely in excess oxygen

C) Fuel burns incompletely due to insufficient oxygen supply

D) Fuel undergoes nuclear decomposition

3 / 20

Particulate matter in air pollution is mainly produced from:

A) Incomplete combustion of carbon-containing fuels

B) Photosynthesis in plants

C) Condensation of water vapor

D) Complete combustion of fuels

4 / 20

Methane in the atmosphere is mainly released from:

A) Industrial chemical reactions

B) Reaction of nitrogen and oxygen in engines

C) Decomposition of vegetation and animal digestion

D) Burning of petrol engines

5 / 20

Oxides of nitrogen are mainly produced by:

A) Burning of plastics at home

B) Photosynthesis in plants

C) Evaporation of fuels

D) Car engines at high temperature

6 / 20

Sulfur dioxide is mainly released from:

A) Burning of sulfur-free fuels

B) Electrolysis of water

C) Decomposition of nitrogen compounds

D) Combustion of fossil fuels containing sulfur compounds

7 / 20

Ground level ozone is formed due to:

A) Decomposition of methane

B) Direct emission from factories

C) Reaction of nitrogen oxides and VOCs in sunlight

D) Burning of hydrogen fuel

8 / 20

Which gas is a primary pollutant but also contributes to secondary pollution?

A) Nitrogen

B) Helium

C) Oxygen

D) Nitrogen oxides

9 / 20

Volatile organic compounds (VOCs) mainly come from:

A) Natural rainfall

B) Solid rock decomposition

C) Pure oxygen cylinders

D) Fuel evaporation and industrial emissions

10 / 20

Which process contributes BOTH carbon monoxide and particulates?

A) Photosynthesis in green plants

B) Incomplete combustion of carbon-based fuels

C) Complete combustion of LPG

D) Electrolysis of water

11 / 20

Why is car exhaust considered a major source of air pollution?

A) It releases only oxygen.

B) It emits CO, NOₓ, particulates and VOCs.

C) It produces only water vapor.

D) It releases nitrogen only.

12 / 20

Methane is classified as an air pollutant mainly because it:

A) is produced by oxygen combustion

B) is a greenhouse gas contributing to climate change

C) is heavier than oxygen

D) reacts with water to form acids

13 / 20

Which of the following is a SECONDARY pollutant?

A) Sulfur dioxide

B) Carbon monoxide

C) Ground level ozone

D) Particulate matter

14 / 20

Sulfur dioxide pollution is most closely associated with:

A) Burning of fossil fuels in power plants

B) Solar energy production

C) Electric vehicles

D) Water electrolysis

15 / 20

Which combination of gases leads to photochemical smog formation?

A) Hydrogen and helium

B) Oxygen and nitrogen

C) Carbon dioxide and methane

D) Nitrogen oxides and VOCs

16 / 20

Decomposition of vegetation mainly contributes to the release of:

A) Carbon monoxide

B) Sulfur dioxide

C) Methane

D) Oxygen

17 / 20

Which is NOT a direct source of air pollution?

A) Photosynthesis in plants

B) Natural decomposition of waste

C) Industrial combustion

D) Vehicle engines

18 / 20

Why are nitrogen oxides considered harmful pollutants?

A) They reduce oxygen levels in water only.

B) They are only naturally produced.

C) They contribute to smog and acid rain formation.

D) They are inert gases.

19 / 20

Which fuel is MOST likely to produce sulfur dioxide on burning?

A) Natural gas without impurities

B) Oxygen gas

C) Coal containing sulfur compounds

D) Pure hydrogen

20 / 20

The main reason incomplete combustion occurs in engines is:

A) Low nitrogen content

B) Insufficient oxygen supply

C) Presence of helium

D) Excess oxygen supply

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