Select the correct statement(s).

Options

A. The non-stoichiometric from of `NaCl` is yellow and that of `KCl` is blue-lilac.
B. Solids containing `F`-centres (Farbe) are paramagentic.
C. Non-stoichiometric compounds are called Berthollide compounds.
D. Conduction by electrons is called `n`-type semiconductor.

Answer

To solve the question regarding the correct statements about solid-state chemistry, we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Option 1: Non-stoichiometric form of NaCl is yellow and that of KCl is blue.**
- **Explanation:** Non-stoichiometric NaCl can exhibit a yellow color due to the presence of F-centers (vacancies in the crystal lattice occupied by unpaired electrons). KCl, when it has F-centers, can appear blue. Therefore, this statement is correct.

2. **Option 2: Solid containing F-centers are paramagnetic.**
- **Explanation:** F-centers are created when an anion vacancy in the crystal lattice is occupied by an unpaired electron. The presence of unpaired electrons makes the solid paramagnetic. Thus, this statement is also correct.

3. **Option 3: Non-stoichiometric compounds are called Berthelite compounds.**
- **Explanation:** Non-stoichiometric compounds are indeed referred to as Berthelite compounds. This statement is correct as it accurately describes these types of compounds.

4. **Option 4: Conduction by electron is called n-type semiconductor.**
- **Explanation:** In n-type semiconductors, conduction is primarily due to the movement of electrons. This statement is correct as it aligns with the definition of n-type semiconductors.

### Conclusion:
All four statements provided in the question are correct.

### Final Answer:
- **All options (1, 2, 3, and 4) are correct.**