The mass of a unit cell of a body centred cubic crystal of a metal is $72.2\times 10^{23}g\mathrm{.}72\; .2\; \backslash times\; 10\; ^\{23\}g.$The atomic mass of the metal is :

An element crystallises in fcc structure. If the atomic mass of the element is 72.7 u, the mass of unit cell of it will be..

Edge length of a cubic unit cell is 354 pm. The distance between two atoms diagonally opposite on the face is

The unit cell has an edge length 403 pm. The distance between two atoms placed opposite ends of body diagonal will be

An element having atomic mass 115 u, crystallises in bcc structure. The number of unit cells in 1 g of the element will be

The edge length of a bcc unit cell of a metallic crystal is 2.9 Å. Hence the diameter of an atom is

An element crystallises in fcc structure. If the atomic radius is 130 pm, the edge length of unit cell is

The arrangement of layers in hexagonal close packing is

For square close packing, the planar arrangement is

Semiconductors are manufactured by addition of impurities of