Separation of mixtures and purification of chemical substances - Jamb Chemistry Past Questions and Answers

Question 36:

• JAMB 1993

Which of the following substances is a mixture?

A. Sulphur powder
B. Bronze
C. Distilled water
D. Ethanol

Question 37:

• JAMB 1993

An experiment produces a gaseous mixtures of carbon (IV) oxide and carbon (II) oxide. In order to obtain pure carbon (II) oxide, the gas mixture should be?

A. Passed over heated copper (II) oxide
B. Bubbled through concentrated tetraoxosulphate (IV) acid
C. Bubbled through sodium hydroxide solution
D. Bubbled through water

Question 38:

• JAMB 1993

A gas that will turn orange potassium heptaoxodichromate (lV) solution to clear green is?

A. Sulphur (ii) oxide
B. Hydrogen sulphide
C. Sulphide (lV) oxide
D. Hydrogen chloride

Question 39:

• JAMB 1993

The function of the copper (ll)tetraoxosulphate (IV) in dilute H₂SO₄ in the figure above is to

A. Dry the gas
B. Absorb phosphine impurity
C. Absorb ethene impurity
D. From an acetylide with ethyne

Question 40:

• JAMB 1993

The dissolution of common salt in water is a physical change because

A. The salt can be obtained by crystallization
B. The salt can be recovered by the evaporation of water
C. Heat is not generated during mixing
D. The solution will not boil at 100^oC