If the distance between $Na^{+}$ and $Cl^{-}$ ions in $NaCl$ crystal is $a \, pm$, what is the length of the cell edge?

The $FCC$ unit cell of a compound contains ions of $A$ at the corners and ions of $B$ at the centre of each face. What is the formula of the compound?

The arrangement of $X^{-}$ ions around $A^{+}$ ion in solid $AX$ is given in the figure. If the radius of $X^{-}$ is $250 \ pm$, the radius of $A^{+}$ is: (in $pm$)

In $NaCl$ type structure, the shortest distance between two nearest neighbours is $100 \ pm$. Then, the distance between two next nearest neighbours in the same unit cell will be:

Argon crystallizes in such a way that the positions of the atoms are at $(0, 0, 0)$,$(0, 1/2, 1/2)$,$(1/2, 0, 1/2)$,and $(1/2, 1/2, 0)$. The type of unit cell is:

$A$ cubic structure is formed where atoms of element $X$ are occupied at the corners of the cube and also at the face centers. Atoms of element $Y$ are present at the body center and at the edge centers. If all the atoms are removed along a plane passing through the middle of the cube (bisecting the four edges), the formula will become