Home / iGCSE Chemistry (0620) Core:10.3 Air quality and climate: Exam Style Questions Paper 1

iGCSE Chemistry (0620) Core:10.3 Air quality and climate: Exam Style Questions Paper 1

iGCSE Chemistry (0620) Core Paper 1 - All Chapters
Question

Which statement describes clean, dry air?

A) It is a compound containing about 78% nitrogen and 21% oxygen only.
B) It is a mixture of about 21% nitrogen and 78% oxygen only.
C) It is a mixture of several gases, including nitrogen and oxygen.
D) It is a compound containing nitrogen, oxygen, carbon dioxide and other gases.

▶️ Answer/Explanation
Solution

Ans: C

Clean, dry air is a mixture (not a compound) of several gases including nitrogen (~78%), oxygen (~21%), and small amounts of other gases like argon and carbon dioxide. The percentages in options A and B are reversed (nitrogen is actually ~78%, not 21%), and option D incorrectly describes air as a compound. Only option C correctly states that air is a mixture of several gases including nitrogen and oxygen.

Question

Some adverse effects caused by air pollutants are listed.

  • acid rain
  • photochemical smog
  • respiratory problems

Which air pollutant contributes to all three of these adverse effects?

A) carbon monoxide
B) oxides of nitrogen
C) methane
D) particulates

▶️ Answer/Explanation
Solution

Ans: B

Oxides of nitrogen (NOx) contribute to all three effects: (1) They dissolve in rainwater to form nitric acid, causing acid rain. (2) They react with hydrocarbons in sunlight to form photochemical smog. (3) They irritate the respiratory system, causing breathing problems. Carbon monoxide (A) mainly causes health issues, methane (C) is a greenhouse gas, and particulates (D) don’t contribute to photochemical smog formation.

Question

Three effects of air pollutants are listed.

  1. photochemical smog
  2. respiratory problems
  3. acid rain

Which effects are caused by oxides of nitrogen?

A) 1, 2 and 3
B) 1 and 3 only
C) 1 only
D) 2 and 3 only

▶️ Answer/Explanation
Solution

Ans: A

Oxides of nitrogen (NOx) contribute to all three effects:

1. Photochemical smog – NOx reacts with volatile organic compounds in sunlight to form smog.

2. Respiratory problems – NOx irritates lungs and can worsen conditions like asthma.

3. Acid rain – NOx reacts with water vapor to form nitric acid, a component of acid rain.

Therefore, all three effects (1, 2, and 3) are caused by oxides of nitrogen, making option A correct.

Question

Which information about carbon dioxide and methane is correct?

▶️Answer/Explanation

Ans:

B

Both carbon dioxide and methane are greenhouse gases. Greenhouse gases are gases in the Earth’s atmosphere that trap heat and contribute to the greenhouse effect, which is essential for maintaining a habitable temperature on our planet.

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