Which is true about water

Options

A. Hardness can be removed by passing through ion exchange resin
B. It is amphoteric
C. It's presence can be detected by unhydrous copper sulphate
D. All

Answer

To determine which statements about water are true, we can analyze the three options provided in the video transcript step by step.

### Step 1: Understanding Hardness of Water
1. **Types of Hardness**: Water can have two types of hardness: temporary hardness and permanent hardness.
2. **Ion Exchange Method**: The ion exchange method is effective in removing permanent hardness from water. This process involves exchanging ions in the water with ions from a resin, effectively softening the water.

**Conclusion**: The statement that hardness can be removed by passing through an ion exchange resin is true.

### Step 2: Amphoteric Nature of Water
1. **Definition of Amphoteric**: An amphoteric substance can act as both an acid and a base.
2. **Examples**:
- When water (H2O) reacts with hydrochloric acid (HCl), it accepts a proton (H+) to form hydronium ion (H3O+), acting as a base.
- When water reacts with ammonia (NH3), it donates a proton (H+) to form hydroxide ion (OH-) and ammonium ion (NH4+), acting as an acid.

**Conclusion**: The statement that water is amphoteric is true.

### Step 3: Testing for Water with Anhydrous Copper Sulfate
1. **Reaction with Anhydrous Copper Sulfate**: Anhydrous copper sulfate (CuSO4) is a white solid. When water is added, it reacts to form hydrated copper sulfate (CuSO4·5H2O), which is blue in color.
2. **Color Change**: The change from white to blue indicates the presence of water.

**Conclusion**: The statement that we can check for the presence of water using anhydrous copper sulfate is true.

### Final Conclusion
Since all three statements about water are true, the correct answer is option D, which states that all the given statements are correct.

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