Ice crystallises in hexagonal lattice having volume of unit cell is `132times10^(-24)cm^(3)`.If density is 0.92g `cm^(3)`at a given temperature, then number of water molecules per unit cell is

Options

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

Explanation

Density , ` d= (Mz)/(N_(0)a^(3))`
where, M = molar mass = 18 g `"mol"^(-1)`
`N_(0)` = Avogadro’s number = `6.022 xx 10^(22)`
Volume =` a^(3)= 132xx10^(-24)cm^(3)`
`:. 0.92 = (18xxz)/(6.02xx10^(23)xx132xx10^(-24))`
`:.` z=4