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 solur is `155 gm mol^(-1)` and that of density is `3.3 gm//cc` the number of formula unit per unit cell is

Options

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

Answer

C

Explanation

`Z = (V xx N_(0) xx d)/(M)`
` = (4.2 xx 8.6 xx 8.3 xx 10^(-24) xx 6.023 xx 10^(23) xx 3.3)/(155)`
` = 3.84 ~~4`