The valancy of carbons is generally `4`, but its oxidation state may be `-4, -2, 0, +2, -1`, etc. In the compounds containing `C, H`, and `O`, the oxidation number of `C` is calculated as
Oxidation number of `C= (2n_(O)-n_(H))/(n_(C ))`
Where `n_(O), n_(H)` and `n_(C )` are the numbers of oxygen, hydrogen, and carbons, atoms, respectively.
In which of the following compounds is the oxidation state of `C` highest?

Options

A. `HCOOH`
B. `HCHO`
C. `CH_(3)OH`
D. `CH_(4)`

Explanation

To determine the compound in which the oxidation state of carbon is highest, we will use the given formula:

\[ \text{Oxidation number of } C = \frac{(2n_O - n_H)}{n_C} \]

where:
- \( n_O \) = number of oxygen atoms
- \( n_H \) = number of hydrogen atoms
- \( n_C \) = number of carbon atoms

We will calculate the oxidation state of carbon for each compound provided.

### Step 1: Calculate for HCOH
- **Number of oxygen (\( n_O \))**: 2
- **Number of hydrogen (\( n_H \))**: 2
- **Number of carbon (\( n_C \))**: 1

Using the formula:

\[ \text{Oxidation number of } C = \frac{(2 \times 2 - 2)}{1} = \frac{(4 - 2)}{1} = \frac{2}{1} = +2 \]

### Step 2: Calculate for HCHO
- **Number of oxygen (\( n_O \))**: 1
- **Number of hydrogen (\( n_H \))**: 2
- **Number of carbon (\( n_C \))**: 1

Using the formula:

\[ \text{Oxidation number of } C = \frac{(2 \times 1 - 2)}{1} = \frac{(2 - 2)}{1} = \frac{0}{1} = 0 \]

### Step 3: Calculate for CH3OH
- **Number of oxygen (\( n_O \))**: 1
- **Number of hydrogen (\( n_H \))**: 4
- **Number of carbon (\( n_C \))**: 1

Using the formula:

\[ \text{Oxidation number of } C = \frac{(2 \times 1 - 4)}{1} = \frac{(2 - 4)}{1} = \frac{-2}{1} = -2 \]

### Step 4: Calculate for CH4
- **Number of oxygen (\( n_O \))**: 0
- **Number of hydrogen (\( n_H \))**: 4
- **Number of carbon (\( n_C \))**: 1

Using the formula:

\[ \text{Oxidation number of } C = \frac{(2 \times 0 - 4)}{1} = \frac{(0 - 4)}{1} = \frac{-4}{1} = -4 \]

### Summary of Results
- For HCOH: Oxidation number of C = +2
- For HCHO: Oxidation number of C = 0
- For CH3OH: Oxidation number of C = -2
- For CH4: Oxidation number of C = -4

### Conclusion
The highest oxidation state of carbon is found in **HCOH**, where the oxidation state is **+2**.

### Final Answer
The compound in which the oxidation state of carbon is highest is **HCOH**.

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