Andre is predicting the products of chemical reactions. In one reaction, a hydrocarbon is the only reactant. What is the best prediction and explanation of this reaction? Two new compounds form as the hydrocarbon undergoes a synthesis reaction. Carbon dioxide and water form because the hydrocarbon undergoes a combustion reaction. A polymer forms because the hydrocarbon joins with itself in a polymerization reaction. Oxides form because the hydrocarbon combines with oxygen in an oxidation reaction.