The correct descending order of the heat liberated (in kJ) during the neutralisation of the acids `CH_(3)COOH ` (W) , HF (X) , HCOOH (Y) and HCN (Z) under identical conditions `K_(a) " of " CH_(3)COOH = 1.8 xx 10^(-5) , ` HCOOH = ` 1.8 xx 10^(-4) , HCN = 4.9 xx 10^(-10) and HF = 3.2 xx 10^(-4)` is

Options

A. ` Y gt X gt Z gt W`
B. `X gt Y gt W gt Z `
C. `W gt X gt Y gt Z`
D. `A gt W gt Y gt X`

Explanation

To determine the correct descending order of the heat liberated during the neutralization of the acids CH₃COOH (W), HF (X), HCOOH (Y), and HCN (Z), we will analyze their acid dissociation constants (Kₐ) provided in the question. The heat liberated during neutralization is directly related to the strength of the acid, which can be inferred from the Kₐ values.

### Step-by-Step Solution:

1. **Identify the Kₐ values:**
- CH₃COOH (Acetic acid) = 1.8 x 10^(-5)
- HCOOH (Formic acid) = 1.8 x 10^(-4)
- HCN (Hydrocyanic acid) = 4.9 x 10^(-10)
- HF (Hydrofluoric acid) = 3.2 x 10^(-4)

2. **Rank the acids based on their Kₐ values:**
- The strength of an acid increases with the increase in Kₐ value. Therefore, we can rank the acids from strongest to weakest based on their Kₐ values:
- HCOOH (1.8 x 10^(-4)) > HF (3.2 x 10^(-4)) > CH₃COOH (1.8 x 10^(-5)) > HCN (4.9 x 10^(-10))

3. **Determine the order of heat liberated:**
- Since stronger acids release more heat during neutralization, we can conclude:
- HF (X) > HCOOH (Y) > CH₃COOH (W) > HCN (Z)

4. **Write the final order:**
- The correct descending order of the heat liberated during the neutralization of the acids is:
- HF (X) > HCOOH (Y) > CH₃COOH (W) > HCN (Z)

### Final Answer:
The correct descending order of the heat liberated during the neutralization of the acids is:
**HF (X) > HCOOH (Y) > CH₃COOH (W) > HCN (Z)**