In a cubic closed packed structure of mixed oxides, the lattice is made up of oxides ions, $20\%$ of tetrahedral voids are occupied by divalent ${\mathrm{X}}^{2+}$ ions and $50\%$ of the octahedral voids are occupied by trivalent ${\mathrm{Y}}^{3+}$ ions. The formula of the oxide is

If $\mathrm{x}=$ radius of ${\mathrm{Na}}^{+}$ and $\mathrm{y}=$ radius of ${\mathrm{Cl}}^{-}$ and $\mathrm{a}$ is the unit cell edge length for $\mathrm{NaCl}$ crystal, then which of the given relation is correct?

A compound ${\mathrm{M}}_{\mathrm{p}}{\mathrm{X}}_{\mathrm{q}}$ has cubic close packing (CCP) arrangement of $\mathrm{X}$. Its unit cell structure is shown below. The empirical formula of the compound is

The unit cell with the following structure refers to______crystal system.

The crystal system of a compound with unit cell dimensions $\mathrm{a}=0.387, \mathrm{b}=0.387 \text{and} \mathrm{c}=0.504 \mathrm{nm}$ and $\mathrm{\alpha }=\mathrm{\beta }=90º \text{and} \mathrm{\gamma }=120º$ is