Density of a crystal remains unchanged as a result of :

Options

A. (a) Ionic defect
B. (b) Schottky defect
C. (c) Frenkel defect
D. (d) Crystal defect

Explanation

To solve the question regarding which defect in a crystal results in unchanged density, we can analyze the two main types of point defects: Frenkel defect and Schottky defect.

### Step-by-Step Solution:

1. **Understanding Crystal Density**:
- Density of a crystal is defined as the mass of the crystal divided by its volume. For a defect to not change the density, the total mass and volume of the crystal must remain constant.

2. **Frenkel Defect**:
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