Question

80 $g$ of water at $30{}^{\circ }C$ is poured on a large block of ice at $0{}^{\circ }C$. The mass of ice that melts is (Latent heat of fusion of ice is $80cal/g$ and specific heat of water is $1cal/g{}^{\circ }C$ )

• A. $30g$
• B. $80g$
• C. $1600g$
• D. $150g$

Answer 1

The correct option is A $30g$

Since, the ice block is very large, so all the poured water cools down to $0{}^{\circ }C$ and the heat rejected in cooling process is taken by ice and it will melt from $0{}^{\circ }C$ ice to $0{}^{\circ }C$ water.

Therefore, by conservation of energy if m mass of ice melts then,
$m\times L=m_{w}S(T_i-T_f)$
$m\times 80=80\times 1\times 30$
$m=30g$
Hence, amount of ice that melts is $30g$.