Assertion (A): There is very little difference in acid strength of `H_(3)PO_(4), H_(3)PO_(3)`,and `H_(3)PO_(2)`.
Reason (R) : The hydrogens in these acids are not all bonded to oxygens. The electrone-grativities of `P` and `H` are almost the same.

Options

A. If both (A) and (R) are correc, and (R) is the correct explanation of (A).
B. If both (A) and (R) are correct but (R) is not the correct explanation of (A).
C. If (A) is correct, but (R) is incorrect.
D. If (A) is incorrect, but (R) is correct.

Explanation

To solve the question regarding the assertion and reasoning about the acid strengths of \( H_3PO_4 \), \( H_3PO_3 \), and \( H_3PO_2 \), we can follow these steps:

### Step 1: Understand the Acids
The acids in question are:
- \( H_3PO_4 \) (Phosphoric acid)
- \( H_3PO_3 \) (Phosphorous acid)
- \( H_3PO_2 \) (Hypophosphorous acid)

### Step 2: Analyze the Structures
1. **Structure of \( H_3PO_4 \)**:
- It has four oxygen atoms. Three of these oxygens are bonded to hydrogen atoms, making it a tribasic acid. The structure can be represented as:
\[ O || P - O - H | O - H | O - H \]

2. **Structure of \( H_3PO_3 \)**:
- It has three oxygen atoms. Two of these are bonded to hydrogen atoms, making it a dibasic acid. The structure can be represented as:
\[ O || P - O - H | O - H | OH \]

3. **Structure of \( H_3PO_2 \)**:
- It has two oxygen atoms. One oxygen is bonded to a hydrogen atom, making it a monobasic acid. The structure can be represented as:
\[ O || P - OH | H \]

### Step 3: Evaluate Acid Strength
- The acidic strength of these acids is determined by the ability of the hydrogen atoms to ionize. The hydrogen atoms that are attached to oxygen are more likely to ionize compared to those attached to phosphorus.
- In all three acids, the hydrogen atoms that are not bonded to oxygen (those bonded to phosphorus) do not ionize due to the similar electronegativities of phosphorus and hydrogen.

### Step 4: Assertion and Reasoning
- **Assertion (A)**: There is very little difference in acid strength among \( H_3PO_4 \), \( H_3PO_3 \), and \( H_3PO_2 \).
- **Reason (R)**: The hydrogens in these acids are not all bonded to oxygens. The electronegativities of \( P \) and \( H \) are almost the same.

### Conclusion
- Both the assertion and reason are true. The reason correctly explains the assertion because the hydrogen atoms that are not bonded to oxygen do not contribute to the acidic strength of the acids.

### Final Answer
Both Assertion (A) and Reason (R) are true, and R is the correct explanation of A.

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