Question

List-I	List-II
(P) Rock salt	(1) Fraction of voids occupied = 1/3
(Q) Zinc Blende	(2) Anion constitute lattice.
(R) Anti-fluorite	(3) Cations in tetrahedral voids.
(S) CsCl type	(4) Co-ordination number of cation and Anion is same
	(5) Cations in octahedral voids.

Which of the following has correct combination on considering List-I and List-II?

• A. P-1, 2, 4, 5
• B. P-1, 2, 3, 4
• C. Q-1, 2, 4, 5
• D. Q-1, 2, 5

Answer 1

Answer: (A)

A

Answer 2

Here is the analysis of each structure from List-I and its corresponding properties from List-II:

(P) Rock salt (e.g., NaCl)

• Structure: Anions (Cl⁻) form an FCC lattice. Cations (Na⁺) occupy all octahedral voids. There are 4 anions and 4 cations per unit cell.
• Lattice: Anion constitute lattice (2) - Yes.
• Cation location: Cations in octahedral voids (5) - Yes. Cations in tetrahedral voids (3) - No.
• Coordination number: Both cation and anion have coordination number 6. Co-ordination number of cation and Anion is same (4) - Yes.
• Voids occupied: In an FCC lattice with 4 anions, there are 4 octahedral voids and 8 tetrahedral voids (total 12 voids). All 4 octahedral voids are occupied by cations. Fraction of total voids occupied = 4/12 = 1/3. Fraction of voids occupied = 1/3 (1) - Yes.
• Matches for P: 1, 2, 4, 5.

(Q) Zinc Blende (e.g., ZnS)

• Structure: Anions (S²⁻) form an FCC lattice. Cations (Zn²⁺) occupy half of the tetrahedral voids (4 out of 8). There are 4 anions and 4 cations per unit cell.
• Lattice: Anion constitute lattice (2) - Yes.
• Cation location: Cations in tetrahedral voids (3) - Yes (half of them). Cations in octahedral voids (5) - No.
• Coordination number: Both cation and anion have coordination number 4. Co-ordination number of cation and Anion is same (4) - Yes.
• Voids occupied: In an FCC lattice with 4 anions, there are 4 octahedral voids and 8 tetrahedral voids (total 12 voids). 4 tetrahedral voids are occupied by cations. Fraction of total voids occupied = 4/12 = 1/3. Fraction of voids occupied = 1/3 (1) - Yes.
• Matches for Q: 1, 2, 3, 4.

(R) Anti-fluorite (e.g., Na₂O)

• Structure: Anions (O²⁻) form an FCC lattice. Cations (Na⁺) occupy all tetrahedral voids (8 out of 8). There are 4 anions and 8 cations per unit cell.
• Lattice: Anion constitute lattice (2) - Yes.
• Cation location: Cations in tetrahedral voids (3) - Yes (all of them). Cations in octahedral voids (5) - No.
• Coordination number: Cation (Na⁺) has CN 4, Anion (O²⁻) has CN 8. Co-ordination number of cation and Anion is same (4) - No.
• Voids occupied: In an FCC lattice with 4 anions, there are 4 octahedral voids and 8 tetrahedral voids (total 12 voids). All 8 tetrahedral voids are occupied by cations. Fraction of total voids occupied = 8/12 = 2/3. Fraction of voids occupied = 1/3 (1) - No.
• Matches for R: 2, 3.

(S) CsCl type

• Structure: Anions (Cl⁻) form a simple cubic lattice. Cations (Cs⁺) occupy the body center. There is 1 anion and 1 cation per unit cell.
• Lattice: Anion constitute lattice (2) - Yes (simple cubic).
• Cation location: Cations in tetrahedral voids (3) - No (in body center). Cations in octahedral voids (5) - No (in body center).
• Coordination number: Both cation and anion have coordination number 8. Co-ordination number of cation and Anion is same (4) - Yes.
• Voids occupied: Not typically described in terms of standard tetrahedral/octahedral voids of FCC/HCP. The body center is occupied. Fraction of voids occupied = 1/3 (1) - Unlikely.
• Matches for S: 2, 4.

Now let's check the given options: (A) P-1, 2, 4, 5: Matches for P are 1, 2, 4, 5. This combination is correct. (B) P-1, 2, 3, 4: P matches 1, 2, 4 but not 3. Incorrect. (C) Q-1, 2, 4, 5: Q matches 1, 2, 4 but not 5. Incorrect. (D) Q-1, 2, 5: Q matches 1, 2 but not 5. Incorrect.

The only correct combination provided in the options is (A).