In the brown ring complex $[Fe(H_2O)_5NO]SO_4$,the primary valency (oxidation state) of $Fe$ is:

One mole of an ideal monoatomic gas $(\gamma = 5/3)$ is mixed with one mole of a diatomic gas $(\gamma = 7/5)$. What is the $\gamma$ for the mixture? Here,$\gamma$ denotes the ratio of specific heat at constant pressure to that at constant volume.

Charge passing through a conductor of cross-section area $A=0.3 ~m^2$ is given by $q=3 t^2+5 t+2$ in coulomb,where $t$ is in second. What is the value of drift velocity at $t=2 ~s$ ? (Given,$n=2 \times 10^{25} / m^3$ )

If $X$ is a Poisson variate such that $\alpha = P(X=1) = P(X=2)$,then $P(X=4)$ is equal to

The wavelengths of electron waves in two orbits is $3: 5$. The ratio of kinetic energy of electrons will be

$A$ current of $2 \, A$ flows in an electric circuit as shown in the figure. The potential difference $(V_R - V_S)$, in volts ($V_R$ and $V_S$ are potentials at $R$ and $S$ respectively) is: