The coordination of $$\mathrm{Ni^2+}$$ is 4.

$$\mathrm{NiCl_2+KCN}$$ (excess) $$\to$$ A (cyano complex)

$$\mathrm{NiCl_2+ conc.~HCl}$$ (excess) $$\to$$ B (chloro complex)

The IUPAC names of $$\mathbf{A}$$ and $$\mathbf{B}$$ are

The edge length of unit cell of a metal having molecular weight $$75 \mathrm{~g} \mathrm{~mol}^{-1}$$ is 5 $$\mathop A\limits^o $$ which crystallizes in cubic lattice. If the density is $$2 \mathrm{~g} / \mathrm{cc}$$, find the radius of metal atom. $$\left(\mathrm{N}_{\mathrm{A}}=6 \times 10^{23}\right)$$. Give the answer in $$\mathrm{pm}$$.