Question

Which of the following is highly inflammable?
(A) Alkenes
(B) Alkanes
(C) Alkynes
(D) None of these

Answer 1

Hint: The substances which have very low explosion temperature and can catch fire easily with a fire are called inflammable substances. For example petrol, alcohol, and Liquefied Petroleum Gas (LPG) are called inflammable substances.

Complete step by step answer:
Inflammable substances and flammable substances both mean combustible substances.
The substance which has low ignition temperature catches fire easily.
Among the given options alkanes, alkenes, and alkynes, saturated hydrocarbons means alkanes are highly inflammable.
The reason why alkanes are highly inflammable is they contain single bonds in their structure. Single bonds can break easily when compared to double and triple bonds. We have to take a lot of care while handling inflammable substances.
When alkenes and alkynes are supposed to react with fire the multiple bonds present in them should break. To break multiple bonds there is a need for a lot of energy.
Therefore alkanes are highly inflammable when compared to alkenes and alkynes.
So, the correct option is B.
Additional information:
Hydrogen gas is highly inflammable gas and it has very less molecular weight.
Kerosene also has low ignition temperature and it is inflammable.
Methane is also a inflammable substance and methane is also called natural gas.

Note: Low ignition temperature means at lowest temperature the substance when heated catches fire in air and continues its combustion to burn. The substances should be saturated to act as inflammable substances. Small saturated hydrocarbons are only called as inflammable substances.