The producers had 6,000 kcal of energy , how much would be passed to the primary consumer?

600 kcal

Explanation:

In an ecosystem, energy is transferred from one organism in a trophic level to another organism in another trophic level. Organisms called PRODUCERS are capable of deriving energy from the sun. However, when fed upon by PRIMARY CONSUMERS, only about 10% of the energy is transferred to them because most of the energy (90%) is lost as heat.

Hence, in this case where the producers had 6,000 kcal of energy, 10% i.e. 10/100 of 6000 = 600 kcal of energy will be transferred to the primary consumers.