Which of the following species acts as an weakest reducing agent?

$$ \text { What is IUPAC name of following compound? } $$

Calculate $\Delta \mathrm{H}^{\circ}$ for a reaction if $\Delta \mathrm{S}^{\circ}=120 \mathrm{JK}^{-1}$ and $\Delta \mathrm{G}^{\circ}=28000 \mathrm{~J}$

Calculate the number of particles present per unit cell if mass of a particle is $8.0 \times 10^{-23} \mathrm{~g} \left[\rho \times a^3=3.2 \times 10^{-22} \mathrm{~g}\right]$