A weak electrolyte obeys Ostwald's dilution law. Select the correct statements.

Options

A. A decrease in concentration of weak acid shows an increase in its degree of dissociation `(alpha)`
B. As `c rarr0` the degree of issociation (`alpha` ) approaches unity
C. A plot of `alpha` versus `(1)/(c )`gives a straight line with slope equal to dissociation constant of weak electrolyte
D. A plotof of `alpha`versus. gives a straight line with slope equal to dissociation constant of weak electrolye

Answer

To solve the question regarding the weak electrolyte and Ostwald's dilution law, let's break down the concepts step by step.

### Step-by-Step Solution:

1. **Understanding Ostwald's Dilution Law**:
Ostwald's dilution law states that for a weak electrolyte, the degree of dissociation (α) is related to its concentration (C) and the dissociation constant (K). The law can be expressed mathematically as:
\[ K_a = C \cdot \alpha^2 \]
where \( K_a \) is the dissociation constant, \( C \) is the concentration of the electrolyte, and \( \alpha \) is the degree of dissociation.

**Hint**: Remember that the degree of dissociation increases as the concentration decreases.

2. **Behavior at Infinite Dilution**:
At infinite dilution, the concentration of the electrolyte approaches zero, and the degree of dissociation approaches unity (α approaches 1). This means that the weak electrolyte will completely ionize at infinite dilution.

**Hint**: Consider what happens to the degree of dissociation as you dilute the solution infinitely.

3. **Effect of Dilution on Degree of Dissociation**:
As the concentration of the weak electrolyte decreases, the degree of dissociation increases. This is a key point to remember when analyzing the behavior of weak electrolytes.

**Hint**: Think about how dilution affects the equilibrium of dissociation reactions.

4. **Graphical Representation**:
When plotting α² against \( \frac{1}{C} \) for weak electrolytes where α is less than 0.05, the plot yields a straight line. The slope of this line is equal to the dissociation constant \( K_a \).

**Hint**: Visualize how the relationship between α and \( \frac{1}{C} \) can help in determining the dissociation constant.

5. **Conclusion**:
Based on the above points, the correct statements regarding weak electrolytes and Ostwald's dilution law can be summarized as:
- A decrease in concentration of a weak acid shows an increase in its degree of dissociation (α).
- At infinite dilution, the degree of dissociation approaches unity.
- A plot of α² versus \( \frac{1}{C} \) gives a straight line with a slope equal to the dissociation constant of the weak electrolyte.

Therefore, options a, b, and c are correct.

### Final Answer:
The correct statements regarding a weak electrolyte obeying Ostwald's dilution law are:
- A decrease in concentration of a weak acid shows an increasing degree of dissociation (α).
- At infinite dilution, the degree of dissociation approaches unity.
- A plot of α² versus \( \frac{1}{C} \) gives a straight line with a slope equal to the dissociation constant of the weak electrolyte.