Which of the following represents a polyatomic ion?

Options

A. Sulphide
B. Chloride
C. Sulphate
D. Nitride

Explanation

To determine which of the given options represents a polyatomic ion, we need to understand what a polyatomic ion is. A polyatomic ion is an ion that consists of two or more atoms bonded together, which carries a net charge.

### Step-by-Step Solution:

1. **Identify the Definition of a Polyatomic Ion**:
- A polyatomic ion is a charged entity composed of two or more atoms.

2. **Examine Each Option**:
- **Option A: Sulfide (S²⁻)**: This ion consists of only one sulfur atom. Therefore, it is not a polyatomic ion.
- **Option B: Chloride (Cl⁻)**: This ion consists of only one chlorine atom. Therefore, it is not a polyatomic ion.
- **Option C: Sulfate (SO₄²⁻)**: This ion consists of one sulfur atom and four oxygen atoms. Since it contains more than one atom, it qualifies as a polyatomic ion.
- **Option D: Nitrate (NO₃⁻)**: This ion consists of one nitrogen atom and three oxygen atoms. Although it has multiple atoms, it is not the correct answer since we are looking for the option that is explicitly mentioned as a polyatomic ion.

3. **Conclusion**:
- Based on the analysis, the correct answer is **Option C: Sulfate (SO₄²⁻)**, as it is the only option that contains more than one atom.

### Final Answer:
**C. Sulfate (SO₄²⁻)** represents a polyatomic ion.