Final answer:
The smallest biomass would be found at the level of the hawk in the given food chain.
Step-by-step explanation:
In the food chain "grass - grasshopper - bird - hawk," the smallest biomass would be found at the level of the hawk. The biomass at each level of the food chain represents the total living mass of organisms. As we move up the food chain, the biomass decreases because each level relies on consuming a larger number of organisms at the lower level to obtain energy and nutrients. Therefore, the top predator in the food chain, which in this case is the hawk, will have the smallest biomass.
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