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

Question 1:

• JAMB 2019

A small quantity of solid ammonium chloride (NH4Cl) was heated gently in a test tube, the solid gradually disappears to produce two gases. Later, a white cloudy deposit was observed on the cooler part of the test tube. The ammonium chloride is said to have undergone

A. Distillation
B. Sublimation
C. Precipitation
D. Evaporation
E. Decomposition

Question 2:

• JAMB 2019

When air which contains the gases Oxygen, nitrogen, carbondioxide, water vapour and the rare gases, is passed through alkaline pyrogallol and then over quicklime, the only gases left are;

A. Nitrogen and carbon dioxide
B. The rare gases
C. Nitrogen and oxygen
D. Nitrogen and the rare gases
E. Nitrogen, carbondioxide and the rare gases

Question 3:

• JAMB 2019

Which of the following changes is physical?

A. Adding iron filing to aerated water
B. Adding sodium metal to water
C. Cooling a solution of Iron (II) sulphate to obtain the hydrated salt
D. Cooling water to obtain ice
E. Burning the domestic gas (Utilgas) for cooking

Question 4:

• JAMB 2019

By means of filtration, one component can be obtained pure from an aqueous mixture of sodium chloride and

A. Potassium nitrate
B. Sand
C. Lead nitrate
D. Sugar (glucose)
E. Starch

Question 5:

• JAMB 1978

A small quantity of solid ammonium chloride (NH₄Cl) was heated gently in a test tube, the solid gradually disappears to produce two gases. Later, a white cloudy deposit was observed on the cooler part of the test tube. The ammonium chloride is said to have undergone

A. Distillation
B. Sublimation
C. Precipitation
D. Evaporation
E. Decomposition