At room temperature, sodium crystallises in a body centred cubic cell with a = 4.24 Å. The theoretical density of sodium is –( Atomic mass of sodium = 23.0 g `mol^(–1))`
(A) 2.05 g `cm^(–3)` (B) 3.45 g` cm^(–3)`
(C) 1.00 g `cm^(–3)` (D) 3.55 g `cm^(–3)`

Explanation

(C )
The value of Z for a bcc unit cell is 2. Volume V = `(4.24 A)^(3) therefore =(ZM)/(NV)=(2xx23)/((6.023xx10^(23))xx(4.24xx10^(-8))^(3)`
=1.00 `g//cm^(3)`