If the number of atoms per unit cell in a crystal is $2$,the structure of the crystal is:

Explain the crystal structure of sodium chloride $(NaCl)$.

$A$ certain metal crystallizes in a $bcc$ lattice. The distance between the nearest neighbours is $433 \text{ pm}$. The distance between the next nearest neighbours is :- .............. $\text{pm}$

$Na$ and $Mg$ crystallise in $b.c.c.$ and $f.c.c.$ type crystals respectively. The number of atoms of $Na$ and $Mg$ present in the unit cell of their respective crystals is:

In an ionic crystal with the general formula $AX$,if the coordination number is $6$,what will be the value of the radius ratio?

$A$ crystal is made up of metal ions $M_1$ and $M_2$ and oxide ions. Oxide ions form a $ccp$ lattice structure. The cation $M_1$ occupies $50 \%$ of octahedral voids and the cation $M_2$ occupies $12.5 \%$ of tetrahedral voids of the oxide lattice. The oxidation numbers of $M_1$ and $M_2$ are,respectively: