4.Which of the following represents a polyatomic ion:Select an answerASulphideBChlorideCSulphateDNitride

The correct answer is C. Sulphate.

A polyatomic ion is an ion composed of two or more atoms.

Step 1: Understand the definition of a polyatomic ion. A polyatomic ion is a charged particle which has two or more atoms held together by covalent bonds.

Step 2: Look at the options given.

Option A: Sulphide - This is a binary compound of sulfur with another element or group and it is not a polyatomic ion.

Option B: Chloride - This is a binary compound of chlorine with another element or group and it is not a polyatomic ion.

Option C: Sulphate - This is a compound with the sulfate ion, SO4^2-, and it is a polyatomic ion.

Option D: Nitride - This is a binary compound of nitrogen with another element or group and it is not a polyatomic ion.

So, the answer is C. Sulphate.