221.

Suppose the mass of a single Ag-atom is m. Ag metal crystallises in fcc lattice with unit cell of length a. The density of Ag metal in terms of a and 'm' is

• $\frac{4\mathrm{m}}{{\mathrm{a}}^3}$

• $\frac{2\mathrm{m}}{{\mathrm{a}}^3}$

• $\frac{\mathrm{m}}{{\mathrm{a}}^3}$

• $\frac{\mathrm{m}}{4{\mathrm{a}}^3}$

Crystalline solids have

• short range order

• long range order

• anisotropic distribution

• All of these.

The number of carbon atoms per unit cell of diamond unit cell is

• 4

• 8

• 6

• 1

A metal has a fcc lattice. The edge length of the unit cell is 404 pm. The density of the metal is 2.72 g cm³. The molar mass of the metal is (N_A  vogadro's constant = 6.02x 10²³ mol^-1).

• 40 g mol^-1

• 30 g mol^-1

• 27g mol^-1

• 20 g mol^-1

What is the co-ordination number of body centred cube ?

• 8

• 6

• 4

• 12

A compound is formed by cation C and anion A. The anions form hexagonal close packed (hcp) lattice and the cations occupy 75% of octahedral voids. The formula of the compound is :

• C₃A₂

• C₃A₄

• C₄A₃

• C₂A₃