The compound forming $ccp$ structure contains $9.6 \times 10^{23}$ atoms. Find the number of tetrahedral voids formed in it.

In a $A_x B_y$ crystal structure,$A^{+y}$ ions occupy all the tetrahedral voids and $B^{-x}$ ions form a $BCC$ unit cell. What is the formula of the compound?

If the unit cell of a mineral has cubic close packed $(ccp)$ array of oxygen atoms with $m$ fraction of octahedral holes occupied by aluminium ions and $n$ fraction of tetrahedral holes occupied by magnesium ions,$m$ and $n$,respectively,are

$A$ 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 $\frac{2}{3}$ of tetrahedral voids. What is the molecular formula of the solid?

Which of the following lattices has the highest packing efficiency: $(i)$ simple cubic,$(ii)$ body-centred cubic,and $(iii)$ hexagonal close-packed lattice?

$A$ compound made up of elements $A$ and $B$ (with a general formula $A_x B_y$),where $B$ forms an $hcp$ lattice and $A$ occupies $2/3$ of the tetrahedral voids. The formula of the compound is