Observation when Quick Lime is Added to Water:
When quick lime (calcium oxide) is added to water, a series of chemical reactions take place. Here is a detailed explanation of the observations made during this process:

1. Heat Generation:
- The addition of quick lime to water is an exothermic reaction, meaning it releases heat. This can be observed by feeling the solution becoming warm to the touch.

2. Formation of Calcium Hydroxide:
- Quick lime reacts with water to form calcium hydroxide (slaked lime). This reaction is highly exothermic and can cause the solution to boil and produce steam.

3. Increase in pH:
- The pH of the solution increases significantly due to the formation of calcium hydroxide, which is a strong base. This can be tested using a inder, which will turn blue in the presence of a base.

4. Formation of a Milky Suspension:
- As the calcium hydroxide is formed, it may not dissolve completely in water and result in a milky suspension. This can be observed as a cloudy appearance in the solution.

5. Settling of Precipitate:
- Over time, the calcium hydroxide formed may settle at the bottom of the container. This can be observed as a white solid settling down.
In conclusion, when quick lime is added to water, the observations include heat generation, formation of calcium hydroxide, increase in pH, formation of a milky suspension, and settling of precipitate. These observations are a result of the chemical reactions taking place between quick lime and water.