In a food chain of frog, grass, insect and snake, assign trophic level to frog.

In the given food chain, the frog occupies the third trophic level (as a secondary consumer).

Food Chain:

$$\text{Grass (Producer)} \rightarrow \text{Insect (Primary Consumer)} \rightarrow \text{Frog (Secondary Consumer)} \rightarrow \text{Snake (Tertiary Consumer)}$$

• First Trophic Level ($T_1$): Grass (Producer)
• Second Trophic Level ($T_2$): Insect (Herbivore / Primary Consumer)
• Third Trophic Level ($T_3$): Frog (Small Carnivore / Secondary Consumer)
• Fourth Trophic Level ($T_4$): Snake (Larger Carnivore / Tertiary Consumer)