Change of State - Jamb Physics Past Questions and Answers

Question 26:

• JAMB 1997

Equal masses of copper and rubber are raised to the same temperature. After sometimes, the copper was observed to be at a lower temperature because

A. The specific heat capacity of copper is lower than that of rubber
B. Copper expands more than rubber
C. The specific heat capacity of rubber is lower than that of copper
D. Rubber expands more than copper

Question 27:

• JAMB 1997

What happens when a, certain quantity of pure ice is completely changed to water at 0oC?

A. Latent heat is absorbed, the mass remains constant, and the volume decreases
B. Latent heat is given out, the mass remains constant and the volume decreases
C. Latent heat is given out, the mass increases and the volume remains constant
D. Latent heat is absorbed, the mass decreases and the volume increases

Question 28:

• JAMB 1997

A heating coil rated at 100W is used to boil off 0.5kg of boiling water. The time taken to boil off the water is [specific latent heat of vaporization of water = 2.3 x 10⁶Jkg^-1]

A. 1.15 x 10⁹ s
B. 1.15 x 10⁷ s
C. 1.15 x 10⁵ s
D. 1.15 x 10⁴ s

Question 29:

• JAMB 1998

How many grams of water at 17^oC must be added to 42g of ice at 0^oC to melt the ice completely? [specific latent heat of fusion of ice = 3.4 x 10⁵Jkg^-1, specific heat capacity of water = 4200Jkg^-1k^-1]

A. 200g
B. 300g
C. 320g
D. 400g

Question 30:

• JAMB 1999

I. A liquid boils when its saturated vapour pressure is equal to the external pressure
II. Dissolved substances in pure water lead to increase in the boiling point.
III. When the external pressure is increased, the boiling point increases.
IV. Dissolved substances in pure water decrease the boiling point.
Which combination of the above are peculiarities of the boiling point of a liquid?

A. I, II and III
B. I, II, III and IV
C. I, II and IV
D. II, III and IV