Question

in all combustion reactions the water (h2o) and carbon dioxide (co2) are while the hydrocarbon and oxygen (o2) are reactants products

Explanation:

In a combustion reaction, hydrocarbons react with oxygen to produce carbon - dioxide and water. Reactants are the starting substances and products are the substances formed. Hydrocarbon and oxygen are the starting substances, so they are reactants. Water and carbon - dioxide are formed, so they are products.

Answer:

Water ($H_2O$) and carbon dioxide ($CO_2$) are products; hydrocarbon and oxygen ($O_2$) are reactants.