Which of the following statements is true of combustion reactions? a. hydrogen gas (h2) must be one of the reactants b. water (h2o) is always a product c. energy is released by the reaction d. carbon monoxide (co2) is always produced

Option (B) is the correct answer.

Explanation:

A chemical reaction in which a hydrocarbon combines with oxygen atom that is present in air to yield carbon dioxide and water along with the products.

For example,

Here, methane undergoes combustion reaction to yield carbon dioxide and water as the products.

Hence, we can conclude that the statement water () is always a product, is true of combustion reactions.