Asource from which organisms generally take elements is called a/an
a. biotic community.
b. reservoir.
c. exchange pool.
d. food web.

C. Exchange pool.

Explanation:

The exchange pool can be define as the pool which includes the elements which are required to be exchanged between the abiotic and biotic components of the environment. This is the part of every biochemical cycle.

On the basis of the above explanation, an exchange pool is the source from which the organisms generally take elements so as to lead their life cycle. For example, the atmosphere is the exchange pool of gaseous elements such as water vapors, oxygen, carbon dioxide and nitrogen. The organisms take oxygen from the atmosphere for respiration and release out carbon dioxide which becomes the part of the atmosphere.

a person with a mass of 106kg has a weight of 1060n