Atoms 'A' are arranged in FCC system. Atoms 'B' are occupied by all the octahedral voids and half of the tetrahedral voids. What is the formula of the compound?

AB₂

The correct answer is option 3. AB₂

Number of atoms of 'A' = \(\frac{1}{8}\) x 8 + \(\frac{1}{2}\) x 6 = 1 + 3 = 4

Number of atoms of 'B' = All O-voids + \(\frac{1}{2}\) x T-voids = 4 + \(\frac{1}{2}\) x 8 = 4 + 4 = 8

A : B = 4 : 8

or A : B = 1 : 2

Hence, the formula of the compound is AB₂.