Which has maximum number of oxo groups ?

Options

A. `H_2SO_4`
B. `H_2SO_3`
C. `H_3PO_3`
D. `H_3PO_4`

Answer

To determine which compound has the maximum number of oxo groups, we need to analyze the structures of the given compounds. An oxo group is defined as a double bond between a carbon (or another atom) and an oxygen atom (C=O or M=O).

Let's evaluate each compound step by step:

### Step 1: Analyze H2SO4 (Sulfuric Acid)
- Structure: H2SO4 has the following structure:
- S double bond O (S=O)
- S double bond O (S=O)
- Two OH groups (–OH)

- Count of oxo groups:
- There are **2 oxo groups** (S=O).

### Step 2: Analyze H2SO3 (Sulfurous Acid)
- Structure: H2SO3 has the following structure:
- S double bond O (S=O)
- One OH group (–OH)
- Another OH group (–OH)

- Count of oxo groups:
- There is **1 oxo group** (S=O).

### Step 3: Analyze H3PO3 (Phosphorous Acid)
- Structure: H3PO3 has the following structure:
- P double bond O (P=O)
- Two OH groups (–OH)

- Count of oxo groups:
- There is **1 oxo group** (P=O).

### Step 4: Analyze H3PO4 (Phosphoric Acid)
- Structure: H3PO4 has the following structure:
- P double bond O (P=O)
- Three OH groups (–OH)

- Count of oxo groups:
- There is **1 oxo group** (P=O).

### Conclusion
After analyzing all the compounds:
- H2SO4 has **2 oxo groups**.
- H2SO3 has **1 oxo group**.
- H3PO3 has **1 oxo group**.
- H3PO4 has **1 oxo group**.

Thus, **H2SO4** has the maximum number of oxo groups.

### Final Answer
The compound with the maximum number of oxo groups is **H2SO4** (option A).

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