What is the value of $x$ and $y$ in order to balance following redox reaction?

$$\mathrm{xCuO}+\mathrm{yNH}_3 \longrightarrow \mathrm{xCu}+\mathrm{N}_2+\mathrm{xH}_2 \mathrm{O}$$

Molar conductivity of 0.02 M weak acid is $7.92 \Omega^{-1} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$ and its molar conductivity at infinite dilution is $232.7 \Omega^{-1} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$. Calculate degree of dissociation of weak acid.

Which from following compounds is most covalent?

What is the total number of atoms present in fcc unit cell?