Question
Which of the following statements about alkanes is true?(A) Alkanes are unsaturated hydrocarbons.(B) Alkanes have a general formula of CₙH₂ₙ.(C) Alkanes contain only single bonds between carbon atoms.(D) Alkanes are more reactive than alkenes.
Answer
(C) is correct: an alkane has single bonds throughout its carbon framework.
- (A) False. Alkanes are saturated, not unsaturated.
- (B) False. The general formula for an acyclic alkane is CₙH₂ₙ₊₂. CₙH₂ₙ instead fits a monocyclic cycloalkane or an acyclic hydrocarbon with one double bond.
- (C) True. Alkanes contain carbon and hydrogen joined by single, sigma bonds.
- (D) False in this introductory comparison. Alkenes have a reactive π bond and readily undergo addition. Alkanes lack that bond, although they can burn and undergo radical substitution under suitable conditions.
Use bonding to identify the class, then apply the formula appropriate to an open chain or a ring.
Evidence boundary
This page uses the four-option version with unsaturation, CₙH₂ₙ, single carbon–carbon bonds, and relative alkene reactivity. The formula comparison treats alkanes as acyclic; monocyclic saturated hydrocarbons are cycloalkanes. Reactivity depends on the reaction and conditions, so the introductory comparison is not a universal ranking for every chemical process.
Sources
These references support the concepts and methods used in the explanation above.