Clarke's process is a water softening method that involves the addition of calcium hydroxide to hard water to precipitate calcium carbonate. This results in the removal of calcium and magnesium ions, which are responsible for causing hardness in water.

The process involves the following steps:

1. Addition of calcium hydroxide: Calcium hydroxide (Ca(OH)2) is added to hard water. The calcium hydroxide reacts with the calcium and magnesium ions in the water to form calcium carbonate and magnesium hydroxide.

Ca(OH)2 + Ca2+ → CaCO3 + 2OH-

2. Precipitation of calcium carbonate: The calcium carbonate formed in the reaction above precipitates out of the water as a solid, along with any other suspended solids in the water.

3. Filtration: The precipitated solids are then filtered out of the water to obtain soft water.

The advantages of using Clarke's process for water softening include:

- It is a simple and low-cost method for water softening
- It does not require the use of chemicals that may be harmful to health or the environment
- It is effective in removing both calcium and magnesium ions from water, which are the main cause of water hardness.

The disadvantages of using Clarke's process for water softening include:

- The process can only remove calcium and magnesium ions, and is not effective in removing other mineral ions that may contribute to water hardness
- The process can lead to the formation of a large amount of sludge, which may require additional treatment or disposal measures.

In conclusion, Clarke's process is an effective and simple method for water softening that involves the addition of calcium hydroxide to hard water. The process is advantageous due to its low cost and lack of harmful chemicals, but may require additional treatment or disposal measures for the sludge formed during the process.

It's becoz Clark's process, is a type of water treatment used for water softening which uses the addition of limewater (calcium hydroxide) to remove hardness (calcium and magnesium) ions by precipitation.