Ice crystallises in a hexagonal lattice having volume of the unit cell as `132 xx 10^(-24) cm`. If its density is `0.92 g cm^(-3)` at a given temperature, then number of `H_(2)O` molecules per unit cell is 

Options

A. 1
B. 2
C. 3
D. 4

Answer

D

Explanation

`d=(m)/(V), m=d xx V=0.92xx132xx10^(-24),n=(m)/(M)=(0.92xx132xx10^(-24))/(18)`
no. of molecules `=nxxN=(0.92xx132xx10^(-24))/(18)xx6.023xx10^(23)=4`