# An ionic compound has a unit cell consisting of A  ions at the corners of a cube and B ions on the centres of the faces of the cube. The empirical formula for this compound would be Option 1) $AB$ Option 2) $A_{2}B$ Option 3) $AB_{3}$ Option 4) $A_{3}B$

As we learnt in

No. of atoms(z) for face centered unit cell -

Lattice points: at corners and face centers of unit cell.

For face centered cubic (FCC), z=4.

- wherein

No. of atoms(z) for simple cubic unit cell -

Lattice points: at corners

For simple cubic (SC), z=1

- wherein

Number of A  ions per unit cell $= \frac{1}{8}\times 8= 1$

Number of B ions per unit cell $= \frac{1}{2}\times6= 3$

$Empirical\: formula\: = AB_{3}$

Correct option is 3.

Option 1)

$AB$

This is an incorrect option.

Option 2)

$A_{2}B$

This is an incorrect option.

Option 3)

$AB_{3}$

This is the correct option.

Option 4)

$A_{3}B$

This is an incorrect option.

N

### Preparation Products

##### JEE Main Rank Booster 2021

This course will help student to be better prepared and study in the right direction for JEE Main..

₹ 13999/- ₹ 9999/-
##### Knockout JEE Main April 2021 (Easy Installments)

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 4999/-
##### Knockout JEE Main April 2021

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 22999/- ₹ 14999/-
##### Knockout JEE Main April 2022

An exhaustive E-learning program for the complete preparation of JEE Main..

₹ 34999/- ₹ 24999/-