Home / iGCSE Chemistry 0620 Extended – 10.3 Air quality and climate- Exam Style Questions Paper 2

iGCSE Chemistry 0620 Extended - 10.3 Air quality and climate- Exam Style Questions Paper 2- New Syllabus

iGCSE Chemistry MCQ (Extended) Paper 2 - All Chapters

Question

The diagram represents two processes, X and Y, and their effect, Z, in increasing global warming.

Which row identifies X, Y and Z?

▶️ Answer/Explanation
Greenhouse gases absorb thermal energy radiated from the Earth’s surface. They then re-emit some of this energy back towards the Earth. The overall effect (Z) is that there is a net reduction in thermal energy loss to space, causing global warming.
✅ Answer: (A)

Question

Three statements about greenhouse gases and global warming are listed.

  1. A greenhouse gas molecule can absorb and emit thermal energy.
  2. The Earth is a source of thermal energy.
  3. Thermal energy emitted by a greenhouse gas molecule is sent out in all directions.

Which statements are correct?

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

▶️ Answer/Explanation
All three statements are correct. Greenhouse gas molecules (like CO₂ and CH₄) absorb infrared (thermal) radiation and re-emit it. The Earth absorbs energy from the Sun and re-emits it as thermal energy. When a greenhouse gas molecule emits thermal energy, it is emitted in all directions — some escapes to space, and some is directed back toward Earth, contributing to the greenhouse effect.
✅ Answer: (A)

Question

Cars are fitted with catalytic converters.

Which equation represents a reaction that takes place in a catalytic converter?

A. \(\mathrm{CO_2 + NO_2 \rightarrow CO + NO + O_2}\)
B. \(\mathrm{2CO + 2NO \rightarrow 2CO_2 + N_2}\)
C. \(\mathrm{CO_2 + N_2 \rightarrow C + 2NO}\)
D. \(\mathrm{C + NO_2 \rightarrow CO + NO}\)

▶️ Answer/Explanation
Catalytic converters in cars convert harmful exhaust gases (carbon monoxide, CO, and nitrogen monoxide, NO) into harmless gases (carbon dioxide, CO₂, and nitrogen, N₂). The reaction is: \(2\mathrm{CO + 2NO \rightarrow 2CO_2 + N_2}\).
✅ Answer: (B)
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