Change of State - Jamb Physics Past Questions and Answers

Question 21:

• JAMB 1987

Calculate the amount of heat required to convert 2kg of ice at 2^oC to water at 0^oC. [specific heat capacity of ice = 2090Jkg^-1oC^-1, specific latent heat of fusion of ice = 333kJkg^-1]

A. 666J
B. 8360J
C. 666 000J
D. 674 360J

Question 22:

• JAMB 1989

An electric heater is used to melt a block of ice of mass 1.5kg. If the heater is powered by a 12V battery and a current of 20A flows through the coil, calculate the time taken to melt the block of ice at 0^oC. [specific latent heat of fusion of ice = 336 x 10³Jkg^-1]

A. 76.0min
B. 35.0min
C. 21.0min
D. 2.9min

Question 23:

• JAMB 1992

A block of ice floats on water inside a container. If the block of ice gets completely melted, the level of water in the container will

A. Increase
B. Remain the same
C. Decrease
D. First decrease and then increase

Question 24:

• JAMB 1994

Heat is supplied to a test tube containing 100g of ice at its melting point. The ice melts completely in 1 min.What is the power rating of the source of heat? [Latent heat of fusion of ice = 336Jg^-1]

A. 336W
B. 450W
C. 560W
D. 600W

Question 25:

• JAMB 1995

Which of the following statements give the TRUE difference between evaporation and boiling? i. Evaporation occurs at all temperatures while boiling occurs at a fixed temperature for a given pressure. ii. Evaporation is a surface phenomenon while boiling is an interior phenomenon. iii. Evaporation is affected by surface area while boiling is not.

A. I and ii only
B. I and iii only
C. Ii and iii only
D. I, ii, iii.