Ferrous oxide `(FeO)` crystal has a cubic structure and each edge of the unit cell is `5.0 A^(@)` Taking density of the oxide as `4.0gcm^(-3)`. The number of `Fe^(2+)` and `O^(2-)` ions present in each unit cell is:

Options

A. 1
B. 2
C. 4
D. 6

Answer

C

Explanation

`d = (Z xx M)/(a^3 xx N_A)`
`4 = (Z xx 72)/((5 xx 10^(-8))^(3) xx (6.02 xx 10^(23)))`
or `Z = (4 xx (5 xx 10^(-8))^(3) xx (6.02 xx 10^(23)))/(72) = 4`
No. of `Fe^(2+)` and `O^(2-)` ions present in each unit cell = 4.