A metal X ( at. Mass = 60) has a body centred cubic crystal structure. The density of the metal is 4.2 g `cm^(-3)` . The volume of unit cell is

Options

A. `8.2 xx 10^(-23) cm^(3)`
B. `4.75 xx 10^(-23) cm^(3)`
C. `3.86 xx 10^(23) cm^(3)`
D. `3.86 xx 10^(-23) cm^(3)`

Answer

B

Explanation

Mass of unit cell `= ( 2 xx 60)/( 6.02 xx 10^(23))`
Density `= ( " Mass")/( "Volume")`
`4.2 = ( 2xx 60)/( 6.02 xx 10^(23) xx v )`
or `V = ( 2 xx 60)/( 6.02 xx 10^(23) xx 4.2 )`
`= 4.75 xx 10^(-23) cm^(3)`