Four samples of natural water from different sources are taken in four petri dishes in equal quantities. These are marked as A, B, C, D and kept in an oven till the entire water vaporizes. When they were taken out, it is observed that sample marked 'C' left maximum amount of residue while sample marked 'B' left negligible amount of residue. 'A' and 'D' left almost same amount of residue.
(a) Identify B and C
(b) Predict the sources of A and D

Explanation

To solve the question, we need to analyze the information given about the four samples of natural water (A, B, C, D) based on the amount of residue left after evaporation.

### Step-by-Step Solution:

1. **Understanding the Residue**:
- After the water samples are evaporated, the residue left behind indicates the presence of dissolved substances (salts, minerals, etc.) in the water.
- A sample that leaves a maximum amount of residue has a high concentration of dissolved substances, while a sample that leaves negligible residue has very few dissolved substances.

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