Question

During vapourisation I. change of state from liquid to vapour state occurs. II. temperature remains constant. III. both liquid and vapour states coexist in equilibrium. IV. specific heat of substance increases. Correct statements are

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

Hint:

During a phase change, heat supplied is used as latent heat, not to raise temperature.

Answer 1

The Correct Option is D

Step 1: During vapourisation, a substance changes its state from liquid to vapour. Hence, statement I is correct.

Step 2: During phase change at constant pressure, the temperature remains constant until the process is complete. Hence, statement II is correct. 

Step 3: During vapourisation, liquid and vapour phases coexist in equilibrium. Hence, statement III is correct. 

Step 4: Specific heat is not defined during phase transition since temperature does not change. Hence, statement IV is incorrect.