In a nuclide,one $a.m.u.$ of mass is dissipated into energy to bind its nucleons. The energy equivalent of this mass is

The relation between the coefficient of real expansion $(\gamma_r)$ and coefficient of apparent expansion $(\gamma_a)$ of a liquid and the coefficient of linear expansion $(\alpha_g)$ of the material of the container is

Assign $A, B, C, D$ from the given type of reaction.
$NaCl + AgNO_3 \longrightarrow AgCl \downarrow + NaNO_3$

If a polygon of $n$ sides has $275$ diagonals,then $n$ is equal to

$A$ convex lens $A$ of focal length $20 \ cm$ and a concave lens $B$ of focal length $5 \ cm$ are kept along the same axis with a distance $d$ between them. If a parallel beam of light falling on $A$ leaves $B$ as a parallel beam,then the distance $d$ in $cm$ will be

For the given figure,if the block remains in an equilibrium position,find the frictional force between the block and the wall in $N$.