Which substance is a primary source of hydrocarbons? a. cottonb. metalsc. petroleum d. soil

The answer is: C. Petroleum.

Petroleum consists of hydrocarbons with between four and twenty carbon atoms.

Petroleum is a mixture of many different hydrocarbons: alkanes (paraffins), cycloalkanes and alkenes (olefins).

Petroleum is used primarily as a fuel in combustion engines.

Most motor oils are made from a heavier, thicker petroleum hydrocarbons.

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.

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