Question

In the following food chain, 20,000 J of energy was available to the plants. How much energy would be available to man in this chain ?

Answer 1

According to $10\%$ law, whatever enery an organism have in a food chain only 10 % of it is tranferred to the next level and 90% of energy is always used up by the organism itself for daily works, body heat ,reproduction,etc.
In the given food chain,
$\text{Plants}\to \text{Sheep}\to \text{Man}20,000\text{J}2000\text{J}200\text{J}$
Amount of energy available to the man is 200 J.