Solid state practice · Mixed difficulty

Option B (8) is correct because in a CsCl lattice, each $Cs^+$ ion is surrounded by 8 $Cl^-$ ions, and vice versa, forming a body-centered cubic (BCC) structure.

Option A (6) is correct because in the NaCl crystal structure, each $\mathrm{Na}^+$ ion is surrounded by six $\mathrm{Cl}^-$ ions, giving it a coordination number of 6.

Option D (Fe3O4) is correct because Fe3O4 (magnetite) is a well-known example of a ferrimagnetic substance.

Option B is correct because the sharp melting point of crystalline solids is due to the regular arrangement of constituent particles observed over a long distance in the crystal lattice.

The correct answer is D (Coordination number of each Na⁺ and Cl⁻ are eight) because in the NaCl crystal structure, the coordination number of each Na⁺ and Cl⁻ ion is 6, not 8.

Option D (All of these) is correct because CuO, $C_O O$, and $Fe_2O_3$ are all oxides that exhibit insulating properties.

Option C is correct because CsF has the largest cation (Cs+) and the smallest anion (F-) among the given options, resulting in the highest cation to anion size ratio.

Option B (3) is correct because body-centered unit cells are present in cubic, tetragonal, and orthorhombic crystal systems, totaling three.

Option B (Crystalline solid) is correct because crystalline solids are characterized by a definite geometrical shape, flat faces, and sharp edges due to their ordered arrangement of atoms.

Option D (8) is correct because a radius ratio greater than 0.732 indicates a coordination number of 8, corresponding to a body-centered cubic structure.

Option D ($0.025 {~N}_{{A}}$) is correct because it is the number of unit cells in 9.6 g of element X with FCC structure, calculated by determining the number of moles and dividing by the number of atoms per unit cell in FCC.

Option C (Very low) is correct because Frenkel defects occur when the radius ratio is very low, allowing the smaller ion to occupy an interstitial site.

Option D (Triclinic) is correct because the triclinic unit cell is characterized by unequal edge lengths ($a \ne b \ne c$) and all axial angles different from 90 degrees ($\alpha \ne \beta \ne \gamma \ne 90^\circ$).

Option C (4) is correct because the percentage of Ni as Ni$^{3+}$ is calculated based on charge balance to maintain neutrality of the compound.

Option B (Both Statement I and Statement II are correct but Statement II is not the correct explanation of Statement I) is correct because both statements are true, but the ionic nature of NaCl doesn't directly explain why NiO has more defects.

Option C (Silver bromide) is correct because AgBr exhibits Frenkel defects due to the significant size difference between Ag+ and Br- ions.

Option D (14) is correct because there are 14 Bravais lattices in three-dimensional space.

Option C (${X_2}Z$) is correct because the ratio of X to Z atoms is 2:1, based on Z occupying ccp and X occupying all tetrahedral sites.

Option A ($A{B_3}$) is correct because the number of atoms of A and B in the unit cell are calculated based on their positions in the FCC lattice, giving a ratio of 1:3.

Option B (0.22 to 0.41) is correct because the ideal radius ratio for tetrahedral coordination is in the range of 0.225 to 0.414.

Option C (Are good conductors of heat and electricity) is correct because metallic crystalline solids have delocalized electrons that facilitate the conduction of heat and electricity.

Option D is correct because it accurately counts the total number of atoms in the unit cell, considering contributions from corners and body diagonals.

Option B (Face centred) is correct because Face-centered cubic (fcc) and hexagonal close-packed (hcp) structures have the highest packing efficiency (74%).

Option B (26 % and 32 %) is correct because the percentage of free space in a cubic close-packed (ccp) structure is 26%, and in a body-centered packed (bcc) structure is 32%.

The correct answer is D. Molecular solids have low melting points and are poor conductors of heat and electricity.

Option D (Si and Ge) is correct because silicon (Si) and germanium (Ge) are the most commonly used semiconductors in transistors.

Option B (0.225) is correct because the ideal radius ratio for a tetrahedral void is between 0.225 and 0.414, with 0.225 being the lower limit.

The correct answer is A (${X_4}{Y_3}$) because the formula is determined by the ratio of atoms X and Y in the crystal lattice, considering the occupancy of tetrahedral voids.

Option B ($\frac{1}{4}$) is correct because an edge-center particle is shared by four unit cells.

Option D is correct because it accurately counts the total number of atoms in the unit cell, considering contributions from corners and body diagonals.