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 a face-centered cubic arrangement of atoms $A$ and $B$,atoms $A$ are at the corners of the unit cell and atoms $B$ are at the face centers. If one atom $A$ is missing from one corner of the unit cell,what is the simplest formula of the compound?

An ionic compound has a unit cell consisting of $A$ ions at the corners of a cube and $B$ ions on the centres of the faces of the cube. The empirical formula for this compound would be

$A$ cubic lattice has atoms of $A$ at the body centre,atoms of $B$ at the corners of the cube and atoms $C$ at all the face centres. What is its formula?

How many nearest neighbours are there for $Si$ and $O$ atoms in quartz crystals?

$A$ compound of $A$ and $B$ crystallises in a cubic lattice in which $A$ atoms occupy the lattice points at the corners of the cube. The $B$ atoms occupy the centre of each face of the cube. The probable empirical formula of the compound is