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0620/42/F/M/21 -Q2 -solved.i

IGCSE  chemistry topic wise solved questions and answers

Selected questions as per  student requests have been solved in the following space

0620/42/F/M/21 -Q2 -solved Note: 2a belongs to topic :diffusion and 2(b) belongs to  topic : air and water

Topic Diffusion solved past papers

Q2(a)The elements shown are gases at room temperature and pressure.

  • hydrogen
  • nitrogen
  • oxygen
  • chlorine

(a) State which one of these gases is green. 


(b) The gases shown exist as diatomic molecules. State the name of another element which has diatomic molecules and is a gas at room temperature and pressure.


(c) When separate samples of each of these gases are placed in a container they will diffuse.

(i) Describe why these gases diffuse

Due to the random motion of  molecules.

(ii) State which of these four gases has the highest rate of diffusion. Explain your answer.

Hydrogen because it has the  lowest (relative) molecular mass 

Topic Air and water solved past papers

(d) Nitrogen, oxygen and other substances are found in clean, dry air.

(i) State the percentage of nitrogen in clean, dry air.  


(ii) Other than nitrogen and oxygen, identify another element found in clean, dry air. 


(iii) Identify a compound found in clean, dry air.

carbon dioxide 

(iv) Nitrogen and oxygen can be separated from liquid air. State the name of this process.

fractional distillation