A solid cube having certain fixed melting and boiling points takes heat from some source. The variation of temperature $\theta$ of the cube with the heat supplied $Q$ is shown in the adjoining graph. The portion $BC$ of the graph represents the conversion of

- A
Solid into vapour

- B
Solid into liquid

- C
Liquid into vapour

- D
Vapour into liquid

Two large holes are cut in a metal sheet. If this is heated, distances $AB$ and $BC$, (as shown)

Two substances $A$ and $B$ of equal mass $m$ are heated at uniform rate of $6\,cal\,s^{-1}$ under similar conditions. A graph between temperature and time is shown in figure. Ratio of heat absorbed $H_A/H_B$ by them for complete fusion is

The coefficient of apparent expansion of mercury in a glass vessel is $153 × 10^{-6}{°C^{-1}}$ and in a steel vessel is $144 × 10^{-6}{°C^{-1}}$. If $\alpha$ for steel is $12 × 10^{-6}{°C^{-1}}$, then that of glass is

$2\,kg$ of metal at $100\,^oC$ is cooled by $1\,kg$ of water at $0\,^oC$ . If specific heat capacity of metal is $\frac {1}{2}$ of specific heat capacity of water, final temperature of mixture would be

Three rods of equal length $l$ are joined to form an equilateral triangle $PQR.$ $O$ is the mid point of $PQ.$ Distance $OR$ remains same for small change in temperature. Coefficient of linear expansion for $PR$ and $RQ$ is same, $i.e., \alpha _2$ but that for $PQ$ is $\alpha _1.$ Then