Write the effect of impurities and external pressure on the freezing point and boiling point of water. Explain with examples.

Explanation

To answer the question regarding the effect of impurities and external pressure on the freezing point and boiling point of water, we can break it down into several steps:

### Step 1: Understanding Freezing Point Depression
- **Definition**: The freezing point of a liquid is the temperature at which it changes from a liquid to a solid.
- **Effect of Impurities**: When impurities (such as salt or sugar) are added to water, the freezing point decreases. This phenomenon is known as freezing point depression.
- **Example**: When salt is added to icy roads, it lowers the freezing point of water, preventing ice from forming at 0°C.

### Step 2: Understanding Boiling Point Elevation
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