The cubic unit cell of `Al` (molar mass 27 g `mol^(-1)` has an edge length of `405` pm. Its density is `2.7` g `cm^(-3)`). The cubic unit cell is

Options

A. face centred
B. body centred
C. primitive
D. edge centred

Answer

C

Explanation

`d=(ZtimesM)/(a^(2)timesN_(0)times10^(-30))`
`"or "Z=(d timesa^(3)timesN_(0)times10^(-30))/M`
=`(2.7times(405)^(3)times(6.02times10^(23))10^(-30))/27=4`
Hence it is face centred cubic unit cell.