Question

Assertion: In rock salt structure, Cl⁻ ions form a close-packed lattice and Na⁺ ions occupy the octahedral voids.

Reason: Sodium chloride possesses a face-centred cubic arrangement.

Options

• If both Assertion and Reason are CORRECT and Reason is the CORRECT explanation of the Assertion.

• If both Assertion and Reason are CORRECT but Reason is not the CORRECT explanation of the Assertion.

• If Assertion is CORRECT but Reason is INCORRECT.

• If Assertion is INCORRECT but Reason is CORRECT.

Answer 1

If both Assertion and Reason are CORRECT and Reason is the CORRECT explanation of the Assertion.

Explanation:

In the rock salt (NaCl) structure, Cl⁻ ions form a face-centred cubic (fcc) close-packed lattice and Na⁺ ions occupy the octahedral voids in that lattice. The fcc arrangement of Cl⁻ ions creates the octahedral voids that Na⁺ ions fill. The Reason directly explains why Na⁺ ions can occupy octahedral voids in the close-packed lattice of Cl⁻ ions.