In which of the following compound oxidation number of Cl is `+3`?

Options

A. Icl
B. `CIO_(3)`
C. `CIF_(3)`
D. `HCIO_(4)`

Explanation

To determine the oxidation number of chlorine (Cl) in the given compounds, we will analyze each compound step by step.

### Step 1: Analyze ICl (Iodine monochloride)
- In ICl, iodine (I) is less electronegative than chlorine (Cl).
- Therefore, iodine will have a positive oxidation state.
- The oxidation state of iodine is +1.
- To balance the compound (which is neutral), chlorine must have an oxidation state of -1.

**Result**: Oxidation number of Cl in ICl = -1.

### Step 2: Analyze ClO3 (Chlorate ion)
- Let the oxidation state of Cl be x.
- The oxidation state of oxygen (O) is -2.
- There are three oxygen atoms, so the total contribution from oxygen is 3 × (-2) = -6.
- The overall charge of the compound is 0 (neutral).

Setting up the equation:
\[ x + (-6) = 0 \]
\[ x = +6 \]

**Result**: Oxidation number of Cl in ClO3 = +6.

### Step 3: Analyze ClF3 (Chlorine trifluoride)
- Let the oxidation state of Cl be x.
- The oxidation state of fluorine (F) is -1.
- There are three fluorine atoms, so the total contribution from fluorine is 3 × (-1) = -3.
- The overall charge of the compound is 0 (neutral).

Setting up the equation:
\[ x + (-3) = 0 \]
\[ x = +3 \]

**Result**: Oxidation number of Cl in ClF3 = +3.

### Step 4: Analyze HClO4 (Perchloric acid)
- Let the oxidation state of Cl be x.
- The oxidation state of hydrogen (H) is +1 and the oxidation state of oxygen (O) is -2.
- There are four oxygen atoms, so the total contribution from oxygen is 4 × (-2) = -8.
- The overall charge of the compound is 0 (neutral).

Setting up the equation:
\[ +1 + x + (-8) = 0 \]
\[ x - 7 = 0 \]
\[ x = +7 \]

**Result**: Oxidation number of Cl in HClO4 = +7.

### Conclusion:
The only compound in which the oxidation number of chlorine is +3 is **ClF3**.

### Summary of Results:
- ICl: Cl = -1
- ClO3: Cl = +6
- ClF3: Cl = +3 (Correct answer)
- HClO4: Cl = +7

### Final Answer:
The oxidation number of Cl is +3 in **ClF3**.

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