Boiling and melting points - Jamb Chemistry Past Questions and Answers

Question 1:

• JAMB 1978

The normal boiling point of a liquid is defined as

A. The temperature at which its vapour pressure equals the atmospheric pressure
B. The temperature at which bubbles begin to form
C. The temperature at which the vapour pressure equals 1 temperature
D. The temperature at which the rate of condensation of vapour equals the rate of vaporisation of the liquid
E. The temperature at which the space above the liquid is saturated

Question 2:

• JAMB 1981

The following compounds are given with their corresponding boiling points.
Compound Boiling Point
i.................................14°C
ii................................24°C
iii................................0°C
iv................................120°C
V.................................-2°C
From the above information, indicate which of the following is correct?

A. All the compounds are gaseous at 20 °C
B. One of the compounds is gaseous at 20 °C
C. Two of the compounds are gaseous at 20 °C
D. Three of the compounds are gaseous at 20 °C
E. None of the compounds is gaseous at 20 °C

Question 3:

• JAMB 1981

The scale formation in a kinetic used for boiling water is caused by the presence in water of?

A. Calcium sulphate
B. Calcium carbonate
C. Calcium hydrogen carbonate
D. Calcium hydroxide
E. Magnesium sulphate

Question 4:

• JAMB 1985

The boiling point of water, ethanol, toluene and butan-2-ol are 373.0k, 351.3k, 383.6k and 372.5k respectively. Which liquid has the highest vapour pressure at 323.0k?

A. Water
B. Toluene
C. Ethanol
D. Butan-2-ol
E. None

Question 5:

• JAMB 1989

Which of the following would support the conclusion that a solid sample is a mixture?

A. The solid can be ground to a fine powder
B. The density of the solid is 2.25 g dm³
C. The solid has a melting range of 300^oC to 375^oC
D. The solid absorbs moisture from the atmosphere