`PH_(4)I +KOH to underset(("gas"))(A) +underset(("salt"))(B) +H_(2)O`
Incorrect statement :-

Options

A. .A. is inflammable gas
B. .B. is salt of (SB + SA)
C. .A. follows Drago.s rule
D. A. is a weaker lewis base than `NH_(3)`

Answer

To analyze the reaction \( PH_4I + KOH \rightarrow \text{(gas)}(A) + \text{(salt)}(B) + H_2O \) and identify the incorrect statement, we will follow these steps:

### Step 1: Write the balanced chemical equation
The reaction involves the interaction of phosphonium iodide (\( PH_4I \)) with potassium hydroxide (\( KOH \)). The products of this reaction can be identified as follows:

1. **Gas (A)**: The gas produced in this reaction is phosphine (\( PH_3 \)).
2. **Salt (B)**: The salt formed is potassium iodide (\( KI \)).
3. **Water**: Water is also produced in the reaction.

Thus, the balanced equation can be written as:
\[ PH_4I + KOH \rightarrow PH_3(g) + KI + H_2O \]

### Step 2: Analyze the statements
Now we will evaluate the statements provided in the question to determine which one is incorrect.

1. **Statement A**: "PH3 is not an inflammable gas."
- This statement is incorrect because phosphine (\( PH_3 \)) is indeed an inflammable gas.

2. **Statement B**: "KI is a salt of a strong acid and a strong base."
- This statement is correct. Potassium iodide (\( KI \)) is formed from the strong acid HI and the strong base KOH.

3. **Statement C**: "PH3 follows Drago's rule."
- This statement is correct. \( PH_3 \) has a lone pair on phosphorus, is from the third period, and the surrounding atoms (hydrogens) have lower electronegativity.

4. **Statement D**: "PH3 is a weaker base than NH3."
- This statement is correct. Due to the larger size of phosphorus compared to nitrogen, \( PH_3 \) is indeed a weaker base than ammonia (\( NH_3 \)).

### Conclusion
The only incorrect statement is **Statement A**: "PH3 is not an inflammable gas."

### Final Answer
The incorrect statement is: **Statement A**.

---