Explain the following:

A glass bottle completely filled with water and tightly closed at room temperature, is likely to burst when kept in the freezer of a refrigerator.

Describe an experiment to show that water has maximum density at 4°C. What important consequences follow from this peculiar property of water? Discuss the importance of this phenomenon in nature.

Out of the following components, which one is not abiotic ?

1. trees
2. light
3. heat
4. rain

Plants use …………… of the total energy absorbed by them in photosynthesis for producing their food.

1. 40%
2. 50%
3. 5%
4. 0.02%