Question

Which of the following is not true about combustion of hydrocarbons?

• A. All hydrocarbons react in sufficient air to form carbon monoxide and then carbon dioxide
• B. Its always an exothermic process
• C. All hydrocarbons react in sufficient air to form carbon dioxide and water
• D. (b) and (c) above.

Answer 1

The correct option is D (b) and (c) above.

In the presence of excess of air, complete combustion of hydrocarbon produces carbon dioxide and water as product
accompanied by evolution of a large amount of heat.
In order to achieve complete combustion, oxygen should be in excess.
for example : $C_3{H}_8+5O_2\to 3C{O}_2+4H_{2}O+Heat$