The correct order of decreasing acidic strength of oxyacids of group 15 elements is

Options

A. `HNO_(3) gt H_(3) SbO_(4) gt H_(3) As O_(4) gt H_(3) PO_(4)`
B. `H_(3) PO_(4) gt H_(3) AsO_(4) gt H_(3) SbO_(4) gt HNO_3`
C. `HNO_(3) gt H_(3) PO_(4) gt H_(3) AsO_(4) gt H_(3) SbO_(4)`
D. `HNO_(3) gt H_(3) AsO_(4) gt H_(3) PO_(4) gt H_(3) SbO_(4)`

Answer

To determine the correct order of decreasing acidic strength of the oxyacids of group 15 elements, we need to analyze the oxidation states of the central atom in each oxyacid. The acidic strength of oxyacids generally increases with the increase in the oxidation state of the central atom. Here’s how we can systematically approach the problem:

### Step-by-Step Solution:

1. **Identify the Oxyacids**: The oxyacids of interest are HClO, HClO2, HClO3, and HClO4.

2. **Calculate the Oxidation States**:
- For **HClO**:
- Let the oxidation state of Cl be \( x \).
- The equation is: \( 1 + x - 2 = 0 \) (since H is +1 and O is -2).
- Solving gives \( x = +1 \).
- For **HClO2**:
- Let the oxidation state of Cl be \( x \).
- The equation is: \( 1 + x - 4 = 0 \) (2 O atoms contribute -4).
- Solving gives \( x = +3 \).
- For **HClO3**:
- Let the oxidation state of Cl be \( x \).
- The equation is: \( 1 + x - 6 = 0 \) (3 O atoms contribute -6).
- Solving gives \( x = +5 \).
- For **HClO4**:
- Let the oxidation state of Cl be \( x \).
- The equation is: \( 1 + x - 8 = 0 \) (4 O atoms contribute -8).
- Solving gives \( x = +7 \).

3. **Determine the Order of Acidity**:
- The oxidation states calculated are:
- HClO: +1
- HClO2: +3
- HClO3: +5
- HClO4: +7
- Since higher oxidation states correspond to stronger acids, the order of acidic strength from strongest to weakest is:
- HClO4 > HClO3 > HClO2 > HClO

4. **Final Order**:
- The correct order of decreasing acidic strength is:
- HClO4 > HClO3 > HClO2 > HClO

### Conclusion:
Thus, the correct answer is that the order of decreasing acidic strength of the oxyacids is:
- **HClO4 > HClO3 > HClO2 > HClO**