Q.1.     A solid is made of two elements X and Y. Atoms X are in fee arrangement and Y atoms occupy all the octahedral sites and alternate tetrahedral sites. What is the formula of the compound?

Q.2.     A compound is formed by two elements M and N. The element N forms ccp and M atom occupy 1/3 of the tetrahedral voids. What is the formula of the compound?

Q.3.     The radius of Na⁺ ion is 95 pm and that of Cl^– ion is 181 pm. Predict whether the coordination number of Na⁺ ion is 6 or 4.

Q.4.     Br^– ions form a close packed structure. If the radius of Br^– ion is 195 pm, calculate the radius of the cation that just fits into the tetrahedral hole. Can a cation having a radius of 82 pm be slipped into the octahedral hole of the crystal A⁺Br^–?

Q.5.     A solid AB has NaCl structure. If the radius of cation A is 100 pm, what is the radius of anion B?

Q.6.     In a crystalline solid, anions Y are arranged in ccp arrangement. Cations X are equally distributed between tetrahedral and octahedral voids. If all the octahedral voids are occupied, what is the formula of the solid?

Q.7.     If the radius of Br^– ion is 0.182 nm, how large a cation can fit in each of the tetrahedral hole?

Q.8.     In a metallic oxide, oxide ions are arranged in cubic close packing. One sixth of the tetrahedral voids are occupied by cations P and one third of octahedral voids are occupied by the cations Q. Deduce the formula of the compound.

Q.9.     In a cubic close packed structure of mixed oxides, the lattice is made up of oxide ions, one–eighth of tetrahedral voids are occupied by divalent ions (A²⁺) while one–half of octahedral voids are occupied by trivalent ions (B³⁺). What is the formula of the oxide?

Q.10.     The mineral spinel has the molecular formula MgAl₂O₄. In this, oxide ions are present in ccp arrangement, Mg²⁺ ions occupy the tetrahedral voids while Al³⁺ ions occupy the octahedral voids. Calculate the percentage of

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