Identify the incorrect statement is regarding the interstitial compounds.

The crystal system with edge lengths $a \neq b \neq c$ and axial angles $\alpha=\beta=\gamma=90^{\circ}$ is ' $x$ ' and number of Bravais lattices for it is ' $y$ '. $x$ and $y$ are

A metal crystallises in simple cubic lattice. The volume of one unit cell is $6.4 \times 10^7 \mathrm{pm}^3$. What is the radius of the metal atom in pm ?

An element occurs in the body centred cubic structure with edge length of 288 pm . The density of the element is $7.2 \mathrm{~g} \mathrm{~cm}^{-3}$. The number of atoms present in 208 g of the element is nearly