Which of the following statements is/are correct?

Options

A. Dislocation of ion from lattice site to interstitial site is called Frenkel defect.
B. Missing of `+ve` and `-ve` ions from their respective position producing a pair of holes is called Schottky defect.
C. The presence of ions in the vacent interstital sites along with lattice point is called interrstital defect.
D. Non-stoichiometric `NaCl` is yellow solid.

Answer

To solve the question regarding which statements about defects in solids are correct, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Option 1: Dislocation of ion from lattice site to interstitial site is called Prandtl defect.**
- This statement is incorrect. The correct term for the dislocation of an ion from its lattice site to an interstitial site is called a **Frenkel defect**, not a Prandtl defect.

2. **Option 2: Missing of positive and negative ions from their respective position producing a pair of hole is called Schottky defect.**
- This statement is correct. In a Schottky defect, both a cation and an anion are missing from the lattice, creating vacancies (or holes) in the structure.

3. **Option 3: Presence of ions in the vacant interstitial site along with lattice point is called interstitial defect.**
- This statement is correct. An interstitial defect occurs when extra ions occupy the interstitial sites in the crystal lattice, in addition to the ions already present at the lattice points.

4. **Option 4: Non-stoichiometric NaCl is a yellow solid.**
- This statement is also correct. When NaCl is non-stoichiometric, particularly when heated in a sodium vapor atmosphere, it can form F-centers (where electrons occupy anionic sites), which imparts a yellow color to the crystal.

### Conclusion:
Based on the analysis:
- **Option 1** is incorrect.
- **Options 2, 3, and 4** are correct.

Thus, the correct statements are Options 2, 3, and 4.