The number of disulphide linkages present in insulin are

$2 \pi - \left(\sin ^{-1} \frac{4}{5} + \sin ^{-1} \frac{5}{13} + \sin ^{-1} \frac{16}{65}\right)$ is equal to

$A$ vertical pole subtends an angle $\tan ^{-1}\left(\frac{1}{2}\right)$ at a point $P$ on the ground. If the angles subtended by the upper half and the lower half of the pole at $P$ are respectively $\alpha$ and $\beta$,then $(\tan \alpha, \tan \beta)$ is equal to

$A$ photon of energy $8\, eV$ is incident on a metal surface of threshold frequency $1.6 \times 10^{15}\, Hz$. The maximum kinetic energy of the emitted photoelectrons is ............. $eV$ $(h = 6.6 \times 10^{-34}\, Js)$.

Among the following compounds,which one is not responsible for the depletion of the ozone layer?

$A$ current-carrying loop is placed in a uniform magnetic field in four different orientations; $I, II, III,$ and $IV.$ Arrange them in the decreasing order of potential energy.