Order `H_(3)PO_(4) gt H_(2)SO_(4) gt HNO_(3) gt HCl` is correct for :-

Options

A. Acidic nature
B. Basic strength
C. Viscosity
D. Oxidation state

Explanation

To determine the correct order of the acids \( H_3PO_4 \), \( H_2SO_4 \), \( HNO_3 \), and \( HCl \), we need to analyze their acidic strengths based on their structures and the oxidation states of the central atoms.

### Step 1: Analyze the structure and oxidation states of each acid.

1. **Orthophosphoric acid (\( H_3PO_4 \))**:
- Structure: \( P \) is bonded to four oxygen atoms, three of which are hydroxyl groups (\( OH \)), and one is a double bond (\( =O \)).
- Oxidation state of phosphorus (P):
- Each \( O \) in \( OH \) contributes -1, and the double-bonded \( O \) contributes -2.
- Therefore, \( P \) has an oxidation state of \( +5 \).

2. **Sulfuric acid (\( H_2SO_4 \))**:
- Structure: \( S \) is bonded to four oxygen atoms, two of which are hydroxyl groups, and two are double-bonded.
- Oxidation state of sulfur (S):
- Each \( O \) in \( OH \) contributes -1, and each double-bonded \( O \) contributes -2.
- Thus, \( S \) has an oxidation state of \( +6 \).

3. **Nitric acid (\( HNO_3 \))**:
- Structure: \( N \) is bonded to three oxygen atoms, one of which is a hydroxyl group, and two are double-bonded.
- Oxidation state of nitrogen (N):
- Each \( O \) in \( OH \) contributes -1, and each double-bonded \( O \) contributes -2.
- Therefore, \( N \) has an oxidation state of \( +5 \).

4. **Hydrochloric acid (\( HCl \))**:
- Structure: \( Cl \) is bonded to one \( H \) and has no oxygen atoms.
- Oxidation state of chlorine (Cl):
- \( Cl \) has an oxidation state of \( +1 \).

### Step 2: Determine the order of acidity based on the oxidation states.

- The acidic strength of these acids is generally related to the oxidation state of the central atom. Higher oxidation states typically correlate with stronger acids because they stabilize the negative charge on the conjugate base more effectively.
- The oxidation states we found are:
- \( H_3PO_4 \): +5
- \( H_2SO_4 \): +6
- \( HNO_3 \): +5
- \( HCl \): +1

### Step 3: Rank the acids based on their acidic strength.

1. **Sulfuric acid (\( H_2SO_4 \))**: Strongest acid due to the highest oxidation state (+6).
2. **Orthophosphoric acid (\( H_3PO_4 \))** and **Nitric acid (\( HNO_3 \))**: Both have an oxidation state of +5, but \( H_3PO_4 \) is generally considered weaker than \( HNO_3 \) due to its structure and the number of dissociable protons.
3. **Hydrochloric acid (\( HCl \))**: Weakest acid with the lowest oxidation state (+1).

### Conclusion:

Thus, the correct order of acidity is:
\[ H_3PO_4 > H_2SO_4 > HNO_3 > HCl \]

### Final Answer:
The order \( H_3PO_4 > H_2SO_4 > HNO_3 > HCl \) is correct for the strength of acids.

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