$A$ block of ice with mass $m$ falls into a lake. After impact,a mass of ice $m/5$ melts. Both the block of ice and the lake have a temperature of $0^{\circ}C$. If $L$ represents the latent heat of fusion,the minimum distance the ice fell before striking the surface is

An experiment takes $10\, minutes$ to raise the temperature of water in a container from $0\,^oC$ to $100\,^oC$ and another $55\, minutes$ to convert it totally into steam by a heater supplying heat at a uniform rate. Neglecting the specific heat of the container and taking the specific heat of water to be $1\, cal/g\,^oC$,the heat of vaporization according to this experiment will be ........ $cal/g$.

Two different liquids of the same mass are kept in two identical vessels, which are placed in a freezer that extracts heat from them at the same rate, causing each liquid to transform into a solid. The schematic figure below shows the temperature $T$ versus time $t$ plot for the two materials. We denote the specific heat in the liquid states as $C_{L 1}$ and $C_{L 2}$ for materials $1$ and $2$, respectively, and the latent heats of fusion as $L_1$ and $L_2$, respectively. Choose the correct option.

An ice cube at temperature $-20^oC$ is kept in a room at temperature $20^oC$. The variation of temperature of the body with time is given by

$Assertion :$ Perspiration from the human body helps in cooling the body.
$Reason :$ $A$ thin layer of water on the skin enhances its emissivity.

Values for latent heat in Column-$I$ and its values are given in Column-$II$. Match the following:

Column-$I$	Column-$II$
$(a)$ Latent heat of vaporization $L_V$	$(i)$ $22.6 \times 10^5 \, J/kg$
$(b)$ Latent heat of fusion $L_f$	$(ii)$ $33.3 \times 10^5 \, J/kg$
	$(iii)$ $3.33 \times 10^5 \, J/kg$