A compound `M_(p)X_(q)` has cubic close packing `(ccp)` arrangement of `X`. Its unit cell structure is shown below. The empirical formula of the compound is

Options

A. MX
B. `MX_2`
C. `M_2X`
D. `M_5X_14`

Answer

B

Explanation

8 X atoms present at the cornes.
Atoms contribute to 1 unit cell =`1/8xx8`=1
6 X atoms present at the face centres.
Atoms contribute to 1 unit cell = `6xx1/2`=3
Total X atoms = 3+1 =4
4 M atoms present at edge centres.
Atoms present in 1 unit cell `=4xx1/4=1`
1 M atom present at body centre and it contribute completely to 1 unit cell .
Thus, total M atoms in one unit cell = 1+1=2
Ratio is M :X : : 2 : 4 : : 1:2
Thus, empirical formula is `MX_2`