Explanation:

Coagulating agents are substances that are used to coagulate or solidify suspended particles in a liquid. They are commonly used in water treatment processes to remove impurities and make the water suitable for various applications.

The coagulating agents mentioned in the options are:
a) Aluminum sulphate
b) Chlorinated copperas
c) Sodium aluminate
d) Copper sulphate

Coagulating agents:
1. Aluminum sulphate: Aluminum sulphate, also known as alum, is a commonly used coagulating agent in water treatment. It is highly effective in removing suspended solids, organic matter, and certain dissolved substances from water. It works by neutralizing the negative charges on the particles, causing them to come together and form larger, easier-to-remove flocs.

2. Chlorinated copperas: Chlorinated copperas, also known as ferric chloride, is another coagulating agent used in water treatment. It is a powerful coagulant and can effectively remove a wide range of impurities from water. It works by destabilizing the particles and forming flocs that can be easily separated from the water.

3. Sodium aluminate: Sodium aluminate is a coagulating agent that is commonly used in water treatment processes. It is a strong alkaline substance that helps in neutralizing the negative charges on suspended particles, thereby allowing them to come together and form larger flocs. These flocs can then be easily removed from the water.

Non-coagulating agent:
4. Copper sulphate: Copper sulphate is not a coagulating agent. It is used for various purposes such as fungicide, algicide, and herbicide. In water treatment, it is sometimes used as an algaecide to control the growth of algae. However, it does not have the ability to coagulate or solidify suspended particles.

Conclusion:
Among the given options, copper sulphate is not a coagulating agent. It is used for other purposes such as controlling algae growth in water treatment processes. The other options mentioned (aluminum sulphate, chlorinated copperas, and sodium aluminate) are all coagulating agents commonly used in water treatment to remove impurities and solids.