An aqueous solution of volume $$300 \mathrm{~cm}^{3}$$ contains $$0.63 \mathrm{~g}$$ of protein. The osmotic pressure of the solution at $$300 \mathrm{~K}$$ is 1.29 mbar. The molar mass of the protein is ___________ $$\mathrm{g} ~\mathrm{mol}^{-1}$$

Given : R = 0.083 L bar K$$^{-1}$$ mol$$^{-1}$$

The number of molecules from the following which contain only two lone pair of electrons is ________

$$\mathrm{H}_{2} \mathrm{O}, \mathrm{N}_{2}, \mathrm{CO}, \mathrm{XeF}_{4}, \mathrm{NH}_{3}, \mathrm{NO}, \mathrm{CO}_{2}, \mathrm{~F}_{2}$$

For a metal ion, the calculated magnetic moment is $$4.90 ~\mathrm{BM}$$. This metal ion has ___________ number of unpaired electrons.

In alkaline medium, the reduction of permanganate anion involves a gain of __________ electrons.