A stationary object at $4°C$ and weighing $3.5\, kg$ falls from a height of $2000\, m$ on a snow mountain at  $0°C$. If the temperature of the object just before hitting the snow is $0°C$ and the object comes to rest immediately $(g = 10\,m/{s^2})$ and (latent heat of ice$ = 3.5 \times {10^5}\,joule/\sec $), then the object will melt

A solid substance is at $30°C$. To this substance heat energy is supplied at a constant rate. Then temperature versus time graph is as shown in the figure. The substance is in liquid state for the portion (of the graph)

The saturation vapour pressure of water at $100°C$ is ........ $mm$ of mercury

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 $J = 4.2\, joule/cal)$

Explain the process of change in state of matter by heating or cooling it.

A metallic ball and highly stretched spring are made of the same material and have the same mass. They are heated so that they melt, the latent heat required