Given colourless liquid will be determined whether it is water or
not?

Options

A. by smelling
B. by tasting
C. by phenolphthalein
D. by adding a pinch of anhydrous `CuSO_(4)`

Explanation

To determine whether a given colorless liquid is water or not, we can follow these steps:

### Step-by-Step Solution:

1. **Observation of Physical Properties**:
- First, note that water is a colorless, odorless, and tasteless liquid. Therefore, we cannot determine if the liquid is water by its appearance, smell, or taste.

2. **Testing with Phenolphthalein**:
- Phenolphthalein is a pH indicator that changes color in response to acidity or alkalinity. Since water is neutral (pH 7), it will not change the color of phenolphthalein. Thus, this test will not help us identify the liquid as water.

3. **Testing with Anhydrous Copper Sulfate (CuSO4)**:
- Anhydrous copper sulfate is a white solid that turns blue when it absorbs water and forms hydrated copper sulfate (CuSO4·5H2O).
- Take a small amount of the colorless liquid and add a pinch of anhydrous copper sulfate to it.

4. **Observation of Color Change**:
- If the liquid is indeed water, the anhydrous copper sulfate will absorb the water and change color from white to blue, indicating the presence of water.
- If there is no color change, the liquid is not water.

5. **Conclusion**:
- Based on the observation of the color change (or lack thereof) when anhydrous copper sulfate is added, you can conclude whether the colorless liquid is water or not.

### Final Answer:
The method to determine whether the colorless liquid is water is by adding a pinch of anhydrous copper sulfate. If it turns blue, the liquid is water.

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