MCQ Detailed View

Hydrocarbons are divided into two main types based on the nature of bonds between carbon atoms: saturated hydrocarbons and unsaturated hydrocarbons. Saturated hydrocarbons contain only single covalent bonds (C–C), while unsaturated hydrocarbons contain one or more double or triple bonds (C=C or C≡C).

The general formula for saturated alkanes is CₙH₂ₙ₊₂. Any hydrocarbon that fits this formula is considered saturated because it holds the maximum number of hydrogen atoms possible.

Let's analyze the given options:

1. 
   

   C₄H₆: Does not fit CₙH₂ₙ₊₂. It has fewer hydrogens, indicating double or triple bonds. Unsaturated.

   
   


2. 
   

   C₅H₁₂: Fits the alkane formula (C₅H₂×₅+₂ = C₅H₁₂). It is a saturated hydrocarbon (alkane).

   
   


3. 
   

   C₃H₄: Has fewer hydrogens than a saturated C₃H₈, meaning it contains multiple bonds. Unsaturated.

   
   


4. 
   

   C₆H₁₀: Less hydrogen than saturated C₆H₁₄, indicating double or triple bonds. Unsaturated.

   
   

From this analysis, C₅H₁₂ is not an unsaturated hydrocarbon because it contains no double or triple bonds. It is a saturated alkane (pentane) with all carbon atoms linked by single covalent bonds.

Unsaturated hydrocarbons are usually alkenes (CₙH₂ₙ) or alkynes (CₙH₂ₙ₋₂). Their ability to undergo addition reactions like hydrogenation or halogenation distinguishes them from saturated hydrocarbons. Alkanes, being saturated, undergo mainly substitution reactions and do not readily add atoms to their structure because all carbon bonds are already single and fully occupied with hydrogen.

Thus, among the given options, C₅H₁₂ is the only saturated hydrocarbon, while the others are unsaturated. This principle helps identify compounds based on their formulas without structural diagrams.