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

The density of water at $20^oC$ is $0.998\, gm/cm^3$ and at $40^oC$ is $0.992\, gm/cm^3$. The mean coefficient of cubical expansion (in per $^oC$) is :-

$50\,g$ of copper is heated to increase is temperature by $10\,^oC$. If the same quantity of heat is given to $10\,g$ of water, the rise in its temperature is  ........ $^oC$ (Specific heat of copper $= 420\,J-kg^{-1}\,^oC^{-1}$ )

Suppose there is a hole in a copper plate. On heating the plate, diameter of hole, would

If the volume of a block of metal changes by $0.12\%$ when it is heated through $20^o\,C$, the coefficient of linear expansion (in per $^oC^{-1}$) of the metal is :-

$540\  g$ of ice at $0\ ^oC$ is mixed with $540\  g$ water at $80\  ^oC$. The final temperature of the mixture is