Change of State - Jamb Physics Past Questions and Answers

Question 6:

• JAMB 1979

All the heat generated in a 5 ohms resistor by 2A flowing for 30 seconds is used to evaporate 5g of a liquid at its boiling point. Which of the following is the correct value of the specific latent heat of the liquid?

A. 120J
B. 60Jg^-1
C. 120Jg^-1
D. 1500J
E. 1500Jg^-1

Question 7:

• JAMB 1980

A given quantity of heat increases the temperature of 150grams of water from 9^oC to 15^oC and increases the temperature of oil of 100grams from 9^oC to 25^oC. The ratio of the specific heat of oil to that of water is

A. 0.36
B. 0.46
C. 0.56
D. 0.76
E. 0.86

Question 8:

• JAMB 1980

Heat is supplied to a block of ice 0^o until half of it has melted. Which of the following statements is true?

A. The temperature rises and the ice exoands
B. The temperature remains constant and the volume of ice decreases
C. The ice gives out heat as it melts
D. The mass remains constant and the temperature increases
E. The mass decreases because some heat is lost to the atmosphere

Question 9:

• JAMB 1980

a calorimeter of thermal capacity 80j contains 20g of water at 25^oC. Water at 100^oC is added so that the final temperature of the set-ups is 50^oC. The amount of water added is (Heat capacity of water = 4.18J/g/^oC)

A. 20g
B. 25g
C. 45g
D. 50g
E. 100g

Question 10:

• JAMB 1981

The latent heat of fusion of a substance is the heat required to

A. Raise the temperature of unit mass of the substance by 1 ^oC
B. Maintain unit mass of the substance at constant temperature
C. Change unit mass of substance from solid to liquid at constant temperature
D. Change unit mass of liquid to vapour at constant temperature
E. Raise the temperature of unit mass by 100^oC