Which of the following is a linear molecule?

The moment of inertia of a uniform semicircular disc of mass $M$ and radius $r$ about a line perpendicular to the plane of the disc passing through its center is:

$A$ charge '$q$' is spread uniformly over an isolated ring of radius '$R$'. The ring is rotated about its natural axis with angular speed $\omega$. The magnetic dipole moment of the ring is

The potential difference between $A$ and $B$ in the figure is .............. $V$.

An ideal gas of mass $m$ in a state $A$ goes to another state $B$ via three different processes as shown in the figure. If ${Q_1}, {Q_2}$ and ${Q_3}$ denote the heat absorbed by the gas along the three paths,then

An $NPN$ transistor circuit is arranged as shown in the figure. It is: