$A$ compound is formed by two elements $M$ and $N$. The element $N$ forms $ccp$ lattice and atoms of $M$ occupy $1/3$ of the tetrahedral voids. What is the formula of the compound?

Which of the following statements is not correct?

In a face-centered cubic $(FCC)$ unit cell (or cubic close packing $(CCP)$ unit cell),the edge length $a$ is equal to:

The packing efficiency of simple cubic $(sc)$, body-centred cubic $(bcc)$ and cubic close packing $(ccp)$ lattices follow the order:

Calculate the volume occupied by all atoms in a $bcc$ unit cell if the volume of the unit cell is $1.5 \times 10^{-22} \ cm^3$.

For the given close-packed structure of a salt made of cation $X$ and anion $Y$ shown below (ions of only one face are shown for clarity),the packing fraction is approximately
$\text{(packing fraction} = \frac{\text{Packing efficiency}}{100}\text{)}$