In the given food chain, suppose the amount of energy at fourth trophic level is 5 kJ, what will be the energy available at the producer level?

Grass → Grasshopper → Frog → Snake → Hawk

In the given food chain fourth trophic level is occupied by snakes. The available energy is 5 kJ at snakes, so at the producer level energy should be 5000 kJ. Grasshopper will get 500 kJ energy as per 10 % law and frog will get 50 kJ and then snake will get 5 kJ energy which is 10 % of 50 kJ.