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JAMB Chemistry 1990 Question 32

Question 32

Qualitative Analysis

Which of the following tests will completely identify any one of sulphur (IV) oxide, hydrogen, carbon (IV) oxide and nitrogen (II) oxide?

  1. A.Pass each gas into water and test with blue litmus paper.
  2. B.Pass each gas into lime water
  3. C.Expose each gas to atmospheric air
  4. D.Pass each gas to concentrated tetraoxosulphate (VI) acid.
Show the answer and explanation

Answer: C (Expose each gas to atmospheric air)

Explanation

Nitrogen(II) oxide is the only one of these gases that changes on meeting air: it turns brown as it forms NO2. Lime water and litmus each give the same result for both SO2 and CO2.