Chemical and physical changes - 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

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 3:

• 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

Question 4:

• JAMB 1978

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 5:

• 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