Vapours - Jamb Physics Past Questions and Answers

Question 1:

• JAMB 1979

When the vapour of a substance is in equilibrium with its own liquid, it is said to be

A. Gaseous
B. Unsaturated
C. Liquefied
D. Diffused
E. Saturated

Question 2:

• JAMB 1981

A vapour is said to be saturated when

A. Moer molecules return to the liquid than leave it
B. A dynamic equilibrium exists between the liquid molecules and the vapour molecules at a given temperature
C. The vapour pressure is atmospheric
D. The temperature of the vapour varies
E. All molecules are moving with the same speed

Question 3:

• JAMB 1984

Dewpoint is the temperature at which, water vapour in the atmosphere

A. Turns into steam
B. Solidifies into ice pellets
C. First condenses into liquid form
D. Is just sufficient to cause cooling
E. Has a relative humidity of fifty percent

Question 4:

• JAMB 1985

Which of the following statements are NOT correct?

A. Boiling occurs when the saturated vapour pressure of the liquid involved equals the external pressure
B. Both the boiling point and the saturated vapour pressure of a given liquid depends on the external pressure
C. The saturated vapour presssure rises with increase in temperature
D. The saturated vapour pressure is independent of the volume available for the vapour
E. It is possible to boil water at a lower temperature than 100^oC at high altitude

Question 5:

• JAMB 1986

Which of the following is common to evaporation and boiling? They

A. Take place at any temperature
B. Are surface phenomena
C. Involve change of state
D. Take place at a definite pressure