In orthorhombic , the value of a, b and c are respectively `4.2Å, 8.6 Å and 8.3Å` .Given the molecular mass of the solute is `155 gm //mol` and that of density is `3.3 gm//cm^3` the number of formula unit per unit cell is

Options

A. 2
B. 3
C. 4
D. 6

Explanation

`z = (V xx N_(0) xx d)/(M) = (4.2xx 8.6 xx 8.3 xx 10^(-24) xx 6.023 xx 10^(-23) xx 3.3)/(155)` Thus, composition of substance = `AB_(3)`.