On the basis of 'charge' complex can be classified into how many types?

Three types

The correct answer is option 3. Three types.

Complexes can be classified based on their charge into three types: cationic, anionic, and neutral complexes. Here’s a detailed explanation:

Cationic Complexes:

These are complexes where the entire complex ion carries a positive charge.

Example: \([ \text{Fe}(\text{H}_2\text{O})_6 ]^{3+}\)

In this example, the central metal ion is iron (Fe) with an oxidation state of +3. Six water molecules (neutral ligands) are coordinated to the iron ion. The overall charge on the complex ion is +3.

Anionic Complexes:

These are complexes where the entire complex ion carries a negative charge.

Example: \([ \text{Fe}(\text{CN})_6 ]^{4-}\)

In this example, the central metal ion is iron (Fe) with an oxidation state of +2. Six cyanide ions (each with a -1 charge) are coordinated to the iron ion. The overall charge on the complex ion is -4.

Neutral Complexes:

These are complexes where the entire complex molecule is neutral, meaning it carries no net charge.

Example: \([\text{Ni}(\text{CO})_4]\)

In this example, the central metal ion is nickel (Ni) with an oxidation state of 0. Four carbon monoxide (CO) molecules (neutral ligands) are coordinated to the nickel ion. The overall charge on the complex molecule is zero.

The classification is based on the net charge of the entire complex ion or molecule, which can be determined by summing the charges on the central metal ion and the ligands attached to it. Therefore, complexes can be classified into three types based on their charge: cationic, anionic, and neutral.