In the given triple point curve as shown in the figure,the curves $AO$,$BO$,and $CO$ represent:

If the ratio of densities of two substances is $5:6$ and the ratio of their specific heat capacities is $3:5$, then the ratio of heat energies required per unit volume so that the two substances can have the same temperature rise is

$A$ block of ice at temperature $-20^{\circ} C$ is slowly heated and converted to steam at $100^{\circ} C$. Which of the following diagrams is most appropriate?

$Assertion :$ In the pressure-temperature $(P-T)$ phase diagram of water,the slope of the melting curve is found to be negative.
$Reason :$ Ice contracts on melting to water.

$A$ beaker is completely filled with water at $4 \text{ } ^\circ C$. When will the water in this beaker overflow?

$A$ piece of ice (heat capacity = $2100 \text{ J kg}^{-1} \text{ }^\circ\text{C}^{-1}$ and latent heat = $3.36 \times 10^5 \ J kg^{-1}$) of mass $m$ grams is at $-5^oC$ at atmospheric pressure. It is given $420 \ J$ of heat so that the ice starts melting. Finally, when the ice-water mixture is in equilibrium, it is found that $1 \ gm$ of ice has melted. Assuming there is no other heat exchange in the process, the value of $m$ is ...... $gm$.