Softening of hard water is done using sodium aluminium silicate (zeolite) . This causes

Options

A. Adsorption of `Ca^(2+)` and `Mg^(2+)` ions of hard water replacing `Na^(o+)` ions.
B. Adsorption of `Ca^(2+)` and `Mg^(2+)` ions of hard water replacing `Al^(3+)` ions.
C. Both (a) and (b) are true
D. None is true

Explanation

To solve the question regarding the softening of hard water using sodium aluminium silicate (zeolite), we can break down the process into several steps:

### Step 1: Understanding Hard Water
Hard water contains high concentrations of calcium (Ca²⁺) and magnesium (Mg²⁺) ions, primarily in the form of carbonates and sulfates. These ions are responsible for the hardness of water.

**Hint:** Identify the ions responsible for water hardness.

### Step 2: Introduction to Zeolite
Zeolites, such as sodium aluminium silicate, are used in water softening processes. They are known for their ability to exchange ions due to their porous structure.

**Hint:** Recall the properties of zeolites that make them effective for softening water.

### Step 3: The Ion Exchange Process
When zeolite is added to hard water, it undergoes an ion exchange process. The zeolite adsorbs the calcium and magnesium ions from the water and releases sodium ions (Na⁺) in their place.

**Hint:** Focus on the mechanism of ion exchange that occurs with zeolite.

### Step 4: Result of the Process
As a result of this ion exchange, the concentration of calcium and magnesium ions in the water decreases, effectively softening the water. The hardness caused by these ions is thus removed.

**Hint:** Consider what happens to the hardness of water after the ion exchange.

### Conclusion
The process that occurs when sodium aluminium silicate (zeolite) is used to soften hard water is the adsorption of Ca²⁺ and Mg²⁺ ions, which are replaced by Na⁺ ions. Therefore, the correct answer to the question is the adsorption of Ca²⁺ and Mg²⁺ ions of hard water, replacing Na⁺ ions.

**Final Answer:** The softening of hard water using sodium aluminium silicate (zeolite) causes the adsorption of Ca²⁺ and Mg²⁺ ions, replacing Na⁺ ions.