Question

Under standard conditions of temperature and pressure a piece of ice melts completely on heating it. Obviously the increase in internal energy of the system (ice and water) is

• A. equal to the heat given.
• B. more than the heat given.
• C. less than the heat given.
• D. zero.

Answer 1

The correct option is B more than the heat given.

we know that When ice melt, volume of water decreases.

so $dW=PdV<0$

$⟹dQ=dU+dW$

$dU=dQ-dW>dQ$

so Under standard conditions of temperature and pressure a piece of ice melts completely on heating it. Obviously the increase in internal energy of the system (ice and water) is more than the heat given.

Hence option B is correct.