In a face centred cubic lattice, atom A occupies the corner positions and atom B occupies the face centre positions. If one atom of B is missing from one of the face centred points, the formula of the compound is :

The edge length of a face centered cubic cell of an ionic substance is 508 pm. If the radius of the cation is 110 pm, the radius of the anion is :

Percentages of free space in cubic close packed structure and in body centred packed structure are respectively :

Copper crystallizes in fcc with a unit cell length of 361 pm. What is the radius of copper atom?