Final answer:
Alkynes, with their carbon-to-carbon triple bonds, are generally the most reactive class of hydrocarbons, more reactive than alkanes, alkenes, and cycloalkanes.
Step-by-step explanation:
In general, alkynes are the most reactive hydrocarbons. The correct answer to the question is B) alkynes. Alkyne hydrocarbons contain a carbon-to-carbon triple bond (R-C≡C-R), making them more reactive than alkenes, which have a double bond, and alkanes, which have only single covalent bonds.
Unlike the more stable cycloalkanes, alkynes exhibit higher reactivity due to the strain and electron density in the triple bond. This aspect of organic chemistry is important to understand as it influences how different hydrocarbons behave in various chemical reactions.
Alkenes and alkynes are the most reactive hydrocarbons among the given options. Alkenes are hydrocarbons with carbon-to-carbon double bonds (R₂C=CR₂), while alkynes are hydrocarbons with carbon-to-carbon triple bonds (R-C=C-R).
These unsaturated hydrocarbons have fewer hydrogen atoms compared to alkanes, which makes them more reactive. For example, alkenes and alkynes can undergo addition reactions with other reagents, whereas alkanes are relatively inert.