A compound is formed by two elements A and B. The element B forms cubic close packed structure and atoms of A occupy 1 3 of tetrahedral voids. If the formula of the compound is A x B y , then the value of x + y is in option

Step-by-step solution

The number of effective atoms per unit cell in the cubic close packed arrangement is 4. Hence, there are four atoms of B per unit cell. In cubic close packed arrangement, there are two tetrahedral voids per atom. So, eight tetrahedral voids are possible. Given that 1 / 3 of tetrahedral voids are occupied. Hence, the possible formula is A 8 3 B 4 and the simplest formula is A 8 B 12 ≡ A 2 B 3 . So, x = 2   &   y = 3 ⇒ x + y = 5