The answer to each of the following is a non-negative integer.
The oxidation state of sulphur atom in `H_2S_2O_7` is……..

Answer

To find the oxidation state of sulfur in \( H_2S_2O_7 \) (also known as oleum or pyrosulfuric acid), we can follow these steps:

### Step 1: Write the chemical formula and identify the elements
The chemical formula is \( H_2S_2O_7 \). It consists of:
- Hydrogen (H)
- Sulfur (S)
- Oxygen (O)

### Step 2: Assign oxidation states to known elements
1. The oxidation state of hydrogen (H) is typically +1.
2. The oxidation state of oxygen (O) is typically -2.

### Step 3: Set up the equation for the total oxidation state
In \( H_2S_2O_7 \):
- There are 2 hydrogen atoms contributing \( 2 \times (+1) = +2 \).
- There are 7 oxygen atoms contributing \( 7 \times (-2) = -14 \).
- Let the oxidation state of sulfur (S) be \( x \). Since there are 2 sulfur atoms, their contribution will be \( 2x \).

### Step 4: Write the equation based on the total charge
The total charge of the molecule is neutral (0), so we can set up the equation:
\[ +2 + 2x - 14 = 0 \]

### Step 5: Solve for \( x \)
Rearranging the equation gives:
\[ 2x - 12 = 0 \]
\[ 2x = 12 \]
\[ x = 6 \]

### Conclusion
The oxidation state of sulfur in \( H_2S_2O_7 \) is +6.