Atoms of B forms fcc lattice and those of element A occupy alternate tetrahedral voids. The formula of the compound formed by elements A and B

\(AB\)

The correct answer is option 3. \(AB\).

Number of particles (atoms, ions or molecules) of \(B\)=\(\frac{1}{8} × 8 + \frac{1}{2} × 3 = 4\) [Since, B forms fcc lattice]

Number of particles (atoms, ions, or molecules) of \(A\) \(= 1 × 4 = 4\) [Since, A occupies alternate tetrahedral voids]

Thus, \(A : B = 4 : 4\)

or, \(A : B = 1 : 1\)

Thus the formula of the compound will be \(AB\).