Which from following cations develops lowest value of spin only magnetic moment?

How long should aqueous NaCl be electrolysed by passing 100 ampere current, so that 0.5 mol chlorine is released at anode?

Calculate the number of atoms present in 1.58 g metal if it forms bcc structure.

$$\left[\rho \times \mathrm{a}^3=1.58 \times 10^{-22} \mathrm{~g}\right]$$

Identify the correct order of thermal stability of hydrides of 16 group elements from the following.