Find the oxidation number of `Cl` in `HCl, HClO,ClO_(4)^(ө)`, and `Ca(Ocl)Cl`.

Explanation

To find the oxidation number of chlorine (Cl) in the compounds HCl, HClO, ClO₄⁻, and Ca(OCl)Cl, we will analyze each compound step by step.

### Step 1: Finding the oxidation number of Cl in HCl
1. **Identify the oxidation states of the other elements:**
- Hydrogen (H) has an oxidation state of +1.
- The overall charge of HCl is 0 (neutral compound).

2. **Set up the equation:**
- Let the oxidation number of Cl be \( x \).
- The equation becomes:
\[ +1 + x = 0 \]

3. **Solve for \( x \):**
\[ x = -1 \]

**Oxidation number of Cl in HCl is -1.**

### Step 2: Finding the oxidation number of Cl in HClO
1. **Identify the oxidation states of the other elements:**
- Hydrogen (H) = +1
- Oxygen (O) = -2
- The overall charge of HClO is 0.

2. **Set up the equation:**
- Let the oxidation number of Cl be \( x \).
- The equation becomes:
\[ +1 + x - 2 = 0 \]

3. **Solve for \( x \):**
\[ x - 1 = 0 \implies x = +1 \]

**Oxidation number of Cl in HClO is +1.**

### Step 3: Finding the oxidation number of Cl in ClO₄⁻
1. **Identify the oxidation states of the other elements:**
- Oxygen (O) = -2
- The overall charge of ClO₄⁻ is -1.

2. **Set up the equation:**
- Let the oxidation number of Cl be \( x \).
- The equation becomes:
\[ x + 4(-2) = -1 \]

3. **Solve for \( x \):**
\[ x - 8 = -1 \implies x = +7 \]

**Oxidation number of Cl in ClO₄⁻ is +7.**

### Step 4: Finding the oxidation number of Cl in Ca(OCl)Cl
1. **Identify the oxidation states of the other elements:**
- Calcium (Ca) = +2
- Oxygen (O) = -2
- The compound is neutral overall.

2. **Set up the equation:**
- Let the oxidation number of Cl in OCl be \( x \) and the other Cl be \( y \).
- The equation becomes:
\[ +2 - 2 + x + y = 0 \]

3. **Since there are two Cl atoms, we can express \( y \) as -1 (the typical oxidation state for Cl in ionic form):**
\[ +2 - 2 + x - 1 = 0 \implies x - 1 = 0 \implies x = +1 \]

4. **Thus, we have:**
- One Cl in OCl has an oxidation state of +1.
- The other Cl is -1.

**Oxidation number of Cl in Ca(OCl)Cl is +1 (in OCl) and -1 (the other Cl).**

### Summary of Oxidation Numbers:
- Cl in HCl: -1
- Cl in HClO: +1
- Cl in ClO₄⁻: +7
- Cl in Ca(OCl)Cl: +1 (in OCl) and -1 (the other Cl)