Question

which of the following is incorrect regarding combustion of alkanes?

• A. It is always an exothermic process
• B. It proceeds through a free radical mechanism
• C. It can be controlled to an intermediate stage
• D. 2-methyl butane will liberate less heat than n-pentane

Answer 1

The correct option is D 2-methyl butane will liberate less heat than n-pentane

2-methyl butane is more reactive than n-pentane in a combustion reaction because former will involve a tertiary free radical.
Hence, 2-methyl butane will liberate more heat than n-pentane. In general branched alkanes will liberate more heat than n-alkanes of comparable molecular weight. Therefore, option (D) is incorrect.