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

Answer

D

Explanation

Density `=(NxxM)/(a^(3)xxN_(A))`
N= Number of molecules, M= Molecular weight
`a^(3)`= volumne `N_(A)`= Avogadro's number
`N= ("Density" xx a^(3) xx N_(A))/(M)`
`=(0.92xx132xx10^(-24) xx 6.023xx 6.023xx10^(23))/(18)`
`=(0.92xx132xx6.023xx10^(-1))/(18)=4.06`