Which of the following are direct products of the combustion of hydrocarbon fuels in automobile engines?

• A. CH_4 and C_2H_6
• B. CO_2 and H_2O
• C. SO_2 and NH_3
• D. O_2 and N_2

Answer: (B)

Verified step by step guidance

1. Understand that combustion of hydrocarbon fuels involves reacting the hydrocarbon with oxygen (O_2) to produce combustion products.
2. Recall that hydrocarbons are compounds made of carbon (C) and hydrogen (H) atoms only, such as CH_4 (methane) and C_2H_6 (ethane).
3. Write the general combustion reaction for a hydrocarbon: \(\text{C}_x\text{H}_y + O_2 \rightarrow \text{products}\).
4. Recognize that complete combustion of hydrocarbons produces carbon dioxide (CO_2) and water (H_2O) as the main products, because carbon atoms form CO_2 and hydrogen atoms form H_2O.
5. Note that SO_2 and NH_3 are not direct products of hydrocarbon combustion, and O_2 and N_2 are reactants or atmospheric gases, not products.