Tetrahedral as well as octahedral interstitial holes are formed by the vacancies left when anions pack in a ccp array. (a) Explain which hole can accommodate the larger ions? (b) Explain what is the size ratio of the largest metal cation that can occupy an octahedral hole to the largest that can take up a tetrahedral hole while maintaining the close-packed nature of the anion lattice? (c) If half the tetrahedral holes are occupied, what will be the empirical formula of the compound MxAy, where M represents the cations and A the anions?