Electrolytes when dissolved in water dissociate into their constituent ions. The degree of dissociation of an electrolyte increases with

Options

A. Increasing the concentration of electrolyte
B. Decreasing the concentration of electrolyte
C. Decreasing temperature
D. Presence of a substance yielding a common ion

Answer

To solve the question regarding the degree of dissociation of an electrolyte when dissolved in water, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Electrolytes**:
- Electrolytes are substances that dissociate into ions when dissolved in water. For example, sodium chloride (NaCl) dissociates into Na⁺ and Cl⁻ ions.

2. **Defining Degree of Dissociation**:
- The degree of dissociation (α) is the fraction of the total number of electrolyte molecules that dissociate into ions. It is represented as a ratio and can range from 0 (no dissociation) to 1 (complete dissociation).

3. **Effect of Concentration**:
- The degree of dissociation is inversely proportional to the concentration of the electrolyte. This means that as the concentration of the electrolyte increases, the degree of dissociation decreases. Therefore, increasing the concentration of the electrolyte will not increase the degree of dissociation.

4. **Effect of Dilution**:
- Conversely, if we decrease the concentration (or dilute the solution), the degree of dissociation increases. This is because there are fewer ions in solution, allowing more of the electrolyte to dissociate. Thus, decreasing the concentration of the electrolyte leads to an increase in the degree of dissociation.

5. **Effect of Temperature**:
- Decreasing the temperature generally leads to an increase in the concentration of the solute, which in turn decreases the degree of dissociation. Therefore, decreasing the temperature does not increase the degree of dissociation.

6. **Common Ion Effect**:
- The presence of a common ion (for example, adding KCl to a NaCl solution increases the concentration of Cl⁻ ions) will also decrease the degree of dissociation of the original electrolyte due to the common ion effect. Hence, this does not lead to an increase in the degree of dissociation.

### Conclusion:
The degree of dissociation of an electrolyte increases with decreasing the concentration of the electrolyte. Therefore, the correct answer is that the degree of dissociation increases with decreasing the concentration of the electrolyte.