The molecular formula of a cystalline solid $X_3 Y_2$. Atoms of $Y$ form ccp lattice and atoms of $X$ occupy $50 \%$ octachedral voids and $X \%$ of tetrahedral voids. What is the percentage of unoccupied tetrahedral voids?

A compound is formed by atoms of $A, B$ and $C$. Atoms of $C$ form hcp lattice. Atoms of $A$ occupy $50 \%$ of octahedral voids and atoms of $B$ occupy $2 / 3$ rd of tetrahedral voids. What is the molecular formula of the solid?

Zinc oxide (white) is heated to high temperature for some time. Observe the following statements regarding above process. I. Zinc oxide colour changes to pale yellow II. The type of defect formed is 'metal deficiency' III. Some $\mathrm{Zn}^{2-}$ and $\mathrm{e}^{-}$are present in interstitial place The correct statements are

Identify the incorrect set from the following.