Home / iGCSE Chemistry Multiple Choice (Extended) : 1.2 Diffusion: Exam Style Questions Paper 2

iGCSE Chemistry Multiple Choice (Extended) : 1.2 Diffusion: Exam Style Questions Paper 2

iGCSE Chemistry MCQ (Extended) Paper 2 - All Chapters
Question

Which gas has the lowest rate of diffusion at room temperature and pressure?

A) the gas produced when ammonium chloride is heated with aqueous sodium hydroxide
B) the gas which makes up approximately 78% of clean, dry air
C) the gas produced when sodium carbonate is added to dilute hydrochloric acid
D) the gas produced when zinc is added to dilute sulfuric acid

▶️ Answer/Explanation
Solution

Ans: C

The rate of diffusion is inversely proportional to the square root of the molar mass (Graham’s Law). Therefore, the gas with the highest molar mass will diffuse the slowest.

Let’s identify each gas:

A) Ammonia (NH₃, M = 17 g/mol) – from heating NH₄Cl with NaOH

B) Nitrogen (N₂, M = 28 g/mol) – 78% of air

C) Carbon dioxide (CO₂, M = 44 g/mol) – from Na₂CO₃ + HCl

D) Hydrogen (H₂, M = 2 g/mol) – from Zn + H₂SO₄

CO₂ has the highest molar mass (44 g/mol), so it will have the lowest rate of diffusion.

Question

Which two gases will diffuse at the same rate, at the same temperature?

  1. carbon monoxide and carbon dioxide
  2. carbon monoxide and nitrogen
  3. chlorine and fluorine
  4. nitrogen and oxygen
Answer/Explanation

Ans:

B

Question

 Which gas has the fastest rate of diffusion?
A. \(H_{2}\)                   B. \(CH_{4}\)                         C. \(CO_{2}\)                      D. \(SO_{2}\)

Answer/Explanation

Ans:

A

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