Which of the following factors will not affect the degree of ionisation ?

Options

A. Temperature
B. Concentration
C. Type of solvent
D. Current

Explanation

To solve the question regarding which factor does not affect the degree of ionization, we can analyze each option provided:

1. **Temperature**: The degree of ionization (α) is affected by temperature. As temperature increases, the kinetic energy of the particles increases, which leads to more frequent and energetic collisions. This results in an increase in the degree of ionization for weak electrolytes. Therefore, temperature does affect the degree of ionization.

2. **Concentration**: The degree of ionization is inversely proportional to the square root of the concentration of the electrolyte. As the concentration of a weak electrolyte decreases, the degree of ionization increases. Thus, concentration does affect the degree of ionization.

3. **Type of Solvent**: The degree of ionization is also influenced by the type of solvent. Polar solvents can stabilize ions better than non-polar solvents, which affects the extent to which a weak electrolyte can dissociate. Therefore, the type of solvent does affect the degree of ionization.

4. **Current**: The degree of ionization is not influenced by the current. While current can affect the movement of ions in an electrolytic solution, it does not change the inherent ability of a substance to ionize in solution. Therefore, current does not affect the degree of ionization.

Based on this analysis, the factor that will not affect the degree of ionization is **current**.

### Final Answer:
The factor that will not affect the degree of ionization is **current** (Option 4).