The graph shown in the figure represent change in the temperature of $5 \,\,kg$ of a substance as it abosrbs heat at a constant rate of $42 \,\,kJ min^{-1}$. The latent heat of vapourazation of the substance is ......... $kJ \,kg^{-1}$

Two different liquids of 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 to be $C_{L 1}$ and $C_{L 2}$ for materials 1 and 2, respectively and latent heats of fusion $U_1$ and $U_2$, respectively. Choose the correct option.

Explain the process of melting of ice with explanation of freezing, melting and melting point.

Fire is extinguished more effectively by

The point on the pressure temperature phase diagram where all the phases co-exist is called

A lead bullet at $27°C$ just melts when stopped by an obstacle. Assuming that $25\%$ of heat is absorbed by the obstacle, then the velocity of the bullet at the time of striking........ $m/sec$  ($M.P.$ of lead $= 327°C,$ specific heat of lead $= 0.03\, cal/gm°C,$ latent heat of fusion of lead $= 6\, cal/gm$ and $J = 4.2\, joule/cal)$