Calculate the number of unit cells in 8.1 g of aluminium if it crystallizes in a face-centred cubic (f.c.c.) structure. (atomic mass of Al=27g `mol^(-1)`)

Explanation

27 g of aluminium has `6.022xx10^(23)` atoms of Al.
8.1 g of aluminium as `(6.022xx10^(23))/(27)xx8.1=1.807xx10^(23)` atoms of Al.
FCC unit cell has 4 atoms of aluminium.
`1.807xx10^(23)` atoms of aluminium has `=(1)/(4)xx1.807xx10^(23)` unit cells
`=4.52xx10^(23)` unit cells.