What is sublimation ? Give name of sublimation substances.
There are certain substances which normally pass from the solid to the vapour state directly and vice versa.
The change from solid state to vapour state without passing through the liquid state is called sublimation, and the substance is said to sublime.
Dry ice (solid $\mathrm{CO}_{2}$ ) sublimes, so also iodine.
During the sublimation process both the solid and vapour states of a substance coexist in thermal equilibrium.
A solid material is supplied with heat at a constant rate. The temperature of material is changing with heat input as shown in the figure. What does slope $DE$ represent.
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 $J = 4.2\, joule/cal)$
Liquid oxygen at $50\ K$ is heated to $300\ K$ at constant pressure of $1\ atm$. The rate of heating is constant which of the following graphs represents the variation of temperature with time
A closed bottle containing water at $30^{\circ} C$ is open on the surface of the moon. Then,
A liquid boils when its vapour pressure equals