`CH_(3)"CCl"_(3)overset("hydrolysis")rarr " acid - 2"`
Correct answer is

Options

A. `(pK_(a))_(HCN) gt (pK_(a))_("acid - 2")`
B. `(pK_(a))_("HCN")=(pK_(a))_("acid - 2")`
C. `(pK_(a))_("HCN")lt (pK_(a))_("acid-2")`
D. All of these

Answer

To solve the problem, we need to analyze the hydrolysis of CH₃CCl₃ and determine the relationship between the pKa values of HCN and the resulting acid (which is acetic acid, CH₃COOH).

### Step-by-Step Solution:

1. **Identify the Reactant:**
The reactant is CH₃CCl₃ (trichloroethane).

2. **Understand the Hydrolysis Reaction:**
Hydrolysis involves the reaction of CH₃CCl₃ with water, resulting in the substitution of chlorine atoms with hydroxyl groups (OH). The reaction can be represented as:
\[ CH₃CCl₃ + H₂O \rightarrow CH₃C(OH)₃ \]

3. **Mechanism of Hydrolysis:**
The hydrolysis of CH₃CCl₃ follows an SN2 mechanism, where the nucleophile (water) attacks the carbon atom bonded to the chlorine atoms, leading to the formation of a tertiary alcohol (CH₃C(OH)₃).

4. **Formation of Acetic Acid:**
The tertiary alcohol (CH₃C(OH)₃) can lose a water molecule to form acetic acid (CH₃COOH):
\[ CH₃C(OH)₃ \rightarrow CH₃COOH + H₂O \]

5. **Determine the pKa Values:**
- The pKa of acetic acid (CH₃COOH) is approximately 4.76.
- The pKa of hydrogen cyanide (HCN) is approximately 9.2.

6. **Compare the Strength of the Acids:**
- Acetic acid is a stronger acid than HCN because it has a lower pKa value.
- The strength of an acid is inversely related to its pKa value; a lower pKa indicates a stronger acid.

7. **Conclusion:**
Since acetic acid is a stronger acid than HCN, we can conclude that:
\[ \text{pKa of acetic acid} < \text{pKa of HCN} \]

### Final Answer:
The correct relationship is:
\[ \text{pKa of acetic acid} < \text{pKa of HCN} \]