Methane reacts with oxygen in the following combustion reaction.

CH4 + 2O2 → CO2 + 2H2O

What bonds are broken in this reaction?

A. Four C-H single bonds and two O=O double bonds

B. Four C-H single bonds

C. One C=O double bond and four O-H single bonds

D. Two O=O double bonds

A. Four C-H single bonds and two O=O double bonds.

Explanation:

The chemical reaction proceeds with breaking bonds in the reacting molecules and forming new bonds in the products. In this reaction four single bonds are broken in CH₄ and two double bonds O=O are broken in two molecules of O₂. Also, two double bonds C=O are formed in CO₂ molecules and 4 single bonds O-H are formed in 2 molecules of H₂O (each molecule contain 2 new bonds). So, A is the right answer.

The methane molecule undergoes oxidation and the carbon is oxidized to carbon dioxide and hydrogen to water.

In this reaction there is cleavage of four C-H bonds and two O=O bonds

there will be formation of two C=O bonds and four O-H bonds.

Overall due to more bond cleavage energy there will be evolution of energy. thus combustion is an exothermic reaction.