The salt of which of the following four weak acids will be most hydrolysed –

Options

A. `HA : K_(a)=1 xx 10^(-8)`
B. `KB : K_(a) =2 xx 10^(-6)`
C. `HC : K_(a) =3 xx 10^(-8)`
D. `KD : K_(a) =4 xx 10^(-10)`

Answer

To determine which salt of the given weak acids will be most hydrolyzed, we need to analyze the acid dissociation constants (Ka) of the weak acids. The degree of hydrolysis (H) is influenced by the Ka value, and we can use the following steps to find the answer.

### Step-by-Step Solution:

1. **Understand Hydrolysis**: Hydrolysis of a salt occurs when it reacts with water to produce an acidic or basic solution. The extent of hydrolysis depends on the strength of the weak acid or weak base from which the salt is derived.

2. **Identify the Given Weak Acids**: Let's assume we have four weak acids with their respective Ka values. For the sake of this solution, let's denote them as:
- Acid A: Ka1
- Acid B: Ka2
- Acid C: Ka3
- Acid D: Ka4

3. **Determine the Relationship Between Ka and Hydrolysis**: The degree of hydrolysis (H) can be expressed as:
\[ H = \sqrt{\frac{K_w}{K_a \cdot K_b}} \]
Where:
- Kw is the ionization constant of water (1.0 x 10^-14 at 25°C).
- Ka is the acid dissociation constant of the weak acid.
- Kb is the base dissociation constant of the conjugate base.

4. **Focus on Ka Values**: Since we are only given the Ka values, we need to find the weakest acid (the one with the smallest Ka value) because a smaller Ka indicates a weaker acid, which leads to more hydrolysis.

5. **Compare the Ka Values**: Examine the provided Ka values for the four weak acids:
- Compare Ka1, Ka2, Ka3, and Ka4 to identify the smallest value.

6. **Identify the Most Hydrolyzed Salt**: The salt derived from the weak acid with the smallest Ka value will undergo the most hydrolysis. Thus, if Ka4 is the smallest, then the salt of Acid D will be the most hydrolyzed.

7. **Conclusion**: Based on the comparison of Ka values, the salt of the weak acid with the lowest Ka will be the one that is most hydrolyzed.