Ineed on the food chain:
consider the following food chain:
- grass absorbs sunlight
- grasshopper eats grass
- snake eats grasshopper
- hawk eats snake

The food chain that is described in the question is called Grazing food chain.

Explanation:

Grazing food chain  is a type of food chain that contain producers at the  lowest tropic level.The producers can manufacture their own food by photosynthesis process. Here grass act as producers.

                       The second topic level of grazing food chain contain primary consumers which consume producer. Here grasshopper eat grass,as a result grasshopper act as primary consumers or herbivores

           The third tropic level of grazing food chain contain secondary consumers that feed on primary consumers. Here snake eats grasshopper,as a result snake act as secondary consumers or primary carnivores.

         The highest tropic level of grazing food chain contain tertiary consumers  or secondary carnivores.Hawk eats snake,as a result hawk act as Tertiary consumers or secondary carnivores.

b. the carbon cycle ensures living things have a source of hydrogen