Please give me answer quickly
Q.20. a) Draw a labelled diagram to illustrate energy flow in eco-system.
b) Calculate the energy obtained by lion, if sun gives energy equals to 2500 J.
Sun $\to$ Grass $\to$ Deer $\to$ Lion
c) Expand OTEC

The diagram illustrates the flow of energy in an ecosystem. Do get back to us for further doubts.

b. 

In an Ecosystem, the transfer of energy in food chain follows the 10%  energy law. According to this law only 10% of energy is transferred from one trophic level to other, rest of energy is either used by the organism or gets lost in the environment. 

Let's apply this law to the question:-

If 2500J is the complete amount of energy available, only 10% of it is transferred to next trophic level.

So, 10% of 2500 is  250J, which is transferred to the grass.

Similarly, 10% of Grass energy(250J) is transferred to deer which is only 25J.

Result- The amount of energy transferred to lion is 2.5J., which is 10% of Deer's energy.

Please ask question in separate thread.

Regards.