JEE MainChemistrySolid State
In a mixed oxide, the oxide ions form a cubic close-packed (ccp) lattice. Metal P occupies 1 8 th of the tetrahedral voids, and metal Q occupies 1 2 of the octahedral voids. If the crystal is electrically neutral, the respective oxidation states of metals P and Q are:
Options
- A+3 and +2
- B+2 and +3
- C+4 and +1
- D+1 and +3
Correct answer
B. +2 and +3
Step-by-step solution
In a ccp lattice of oxide ions, the number of O ²⁻ ions per unit cell is 4 . The number of tetrahedral voids is 2 4 = 8 . Number of P atoms = 1 8 8 = 1 . The number of octahedral voids is 4 . Number of Q atoms = 1 2 4 = 2 . The empirical formula of the mixed oxide is PQ ₂ O ₄ . For the crystal to be electrically neutral, the sum of the oxidation states must be zero. Let the oxidation state of P be x and that of Q be y . 1(x) + 2(y) + 4(-2) = 0 x + 2y = 8 Checking the given options: For +3 and +2 : 3 + 2(2) = 7 8 Fo