At the producer level, if 20J of energy is trapped, then how much energy will be available to a peacock as food in the subsequent chain?

Plant -> Mice -> Snake -> Peacock

The correct option is 0.02 J.

To understand why this is correct, we can apply Lindeman's 10% Law of energy transfer in a food chain. According to this ecological principle, only about 10% of the energy available at a particular trophic level is transferred to the next higher trophic level. The remaining 90% of the energy is lost to the environment as heat during respiration and other metabolic processes, or remains unconsumed.

Let us analyze the given food chain step-by-step, starting from the producers (Plants):

1. Producer Level (Plant):
The energy trapped by the plant is given as:
$E_{\text{Plant}}=20\text{J}$

2. Primary Consumer Level (Mice):
Mice feed on plants. The energy available to mice is 10% of the energy at the plant level:
$E_{\text{Mice}}=10\%\text{of}20\text{J}=\frac{10}{100}\times 20\text{J}=2\text{J}$

3. Secondary Consumer Level (Snake):
Snakes feed on mice. The energy available to snakes is 10% of the energy at the mice level:
$E_{\text{Snake}}=10\%\text{of}2\text{J}=\frac{10}{100}\times 2\text{J}=0.2\text{J}$

4. Tertiary Consumer Level (Peacock):
Peacocks feed on snakes. The energy available to the peacock is 10% of the energy at the snake level:
$E_{\text{Peacock}}=10\%\text{of}0.2\text{J}=\frac{10}{100}\times 0.2\text{J}=0.02\text{J}$

Therefore, the amount of energy available to the peacock as food in this chain is 0.02 J.