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

Question 41:

• JAMB 1994

A pure solid usually melts?

A. Over a wide range of temperature
B. Over a narrow range of temperature
C. At a lower temperature than the impure one
D. At the same temperature as the impure one

Question 42:

• JAMB 1995

Chromatography is used to separate components of mixtures which differ in their rates of?

A. Diffusion
B. Migration
C. Reaction
D. Sedimentaion

Question 43:

• JAMB 1995

Chromatography is used to separate components of mixtures which differ in their rates of?

A. Diffusion
B. Migration
C. Reaction
D. Sedimentaion

Question 44:

• JAMB 1995

Which of the following is a example of a chemical change?

A. Dissoultion of salt in water
B. Rusting of iron
C. Melting of ice
D. Separating a mixture by distillation

Question 45:

• JAMB 1995

A liquid begins to boil when?

A. Its vapour pressure is equal to the vapour pressure of its solid at the given temperature
B. Molecules start escaping from its surface
C. Its vapour pressure equals the atmosphere pressure
D. Its volume is sightly increased