Aluminium has fcc structure. The length of the unit cell is 409 pm. If the density of the metal is `2.7 g" " cm^(-3)`, the molar mass of Al atom is

Options

A. 28 g `mol^(-1)`
B. 30 g `mol^(-1)`
C. 26.80 g `mol^(-1)`
D. 25 g `mol^(-1)`

Answer

C

Explanation

`M=(rhoa^(3)N_(A))/Z`
`((2.7times404times10^(-10))times6.023times10^(23))/4`
26.80 g`mol^(-1)`[Z=4,f.c.c.]