Question

The diagram shows the change of phase of a substance on a temperature-time graph. Which of the following is/are true?

• A. BC part - melting at temperature $t_1{}^{\circ }C$
• B. CD part - rise in temperature of liquid from $t_1{}^{\circ }C$ to $t_3{}^{\circ }C$
• C. DE part - boiling at temperature $t_3{}^{\circ }C$.
• D. All of the above

Answer 1

Answer: (D)

All the above.

In part $AB$, state is solid and temperature is rising.

In part $BC$, there is change of state from solid to liquid, i.e., this stage is melting, without change in temperature.

In part $CD$, state is liquid and temperature is rising.

In part $DE$, there is change of state from liquid to gas, i.e., this stage is vaporization, without change in temperature.

In part $EF$, state is gas and temperature is rising.