Question

Assertion : The presence of a large number of Schottky defects in NaCl lowers its density.

Reason : n NaCl, there are approximately 10⁶ Schottky pairs per cm³ at room temperature.

(a) Both A and R are true and R is the correct explanation of A

(b) Both A and R are true but R is not correct explanation of A

(c) A is true but R is false

(d) A and R are false

Answer 1

Correct option (b) Both A and R are true but R is not correct explanation of A

Explanation:

When an atom or an ion is missing from its normal lattice site, a lattice vacancy or defect is created, which is called Schottky defect. Due to missing atoms or ions, density of the crystal will be lowered.