(a) Name and state the law given by Lindeman which tells us how much energy entering a particular trophic level of organisms is available for transfer to the next higher trophic level.
(b) How much energy will be available to hawks in the food chain comprising hawk, snake, paddy and mice, if 10,000 J of energy is available to paddy from the sun ?

Answer

### Step-by-Step Solution:

**(a)** The law given by Lindeman is known as the **10% Law**. This law states that when energy is transferred from one trophic level to the next in an ecosystem, only about **10%** of the energy from the previous level is available for transfer to the next higher trophic level. The remaining **90%** of the energy is lost primarily as heat due to metabolic processes and other biological activities.

**(b)** To determine how much energy will be available to hawks in the food chain comprising hawk, snake, paddy, and mice, we start with the energy available to paddy from the sun, which is **10,000 J**.

1. **Energy available to Paddy (Producers)**: 10,000 J (from the sun).
2. **Energy available to Mice (Primary Consumers)**:
- According to the 10% Law, only 10% of the energy from paddy is transferred to the mice.
- Energy available to mice = 10% of 10,000 J = 1,000 J.
3. **Energy available to Snake (Secondary Consumers)**:
- Again, applying the 10% Law, only 10% of the energy from mice is transferred to the snake.
- Energy available to snake = 10% of 1,000 J = 100 J.
4. **Energy available to Hawk (Apex Consumers)**:
- Finally, applying the 10% Law once more, only 10% of the energy from the snake is transferred to the hawk.
- Energy available to hawk = 10% of 100 J = 10 J.

Thus, the energy available to hawks in this food chain is **10 J**.