Which of the following unsaturated hydrocarbons contains a triple bond?

Appeared in: RRB Nsg. Superintendent - 29 April 2025 (Shift-3rd)

Explanation

Ethyne is classified as an alkyne, which is a type of unsaturated hydrocarbon.
The defining characteristic of alkynes is the presence of at least one carbon-carbon triple bond (C≡C).
The suffix '-yne' in the name 'Ethyne' specifically indicates the presence of this triple bond.

Option A: Methane is an alkane, which is a saturated hydrocarbon. It contains only single carbon-hydrogen bonds and no carbon-carbon bonds.
Option B: Ethane is an alkane, a saturated hydrocarbon. It contains only a single carbon-carbon bond (C-C), not a triple bond.
Option C: Propene is an alkene. While it is an unsaturated hydrocarbon, it is characterized by a carbon-carbon double bond (C=C), not a triple bond.

Visual 1: Diagram: Molecular structures of Methane (CH₄), Ethane (C₂H₆), Propene (C₃H₆), and Ethyne (C₂H₂), clearly illustrating the single, double, and triple bonds between carbon atoms.
Visual 2: Table: A summary table classifying hydrocarbons into alkanes, alkenes, and alkynes with their respective general formulas, bond types, and naming suffixes.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification and nomenclature of hydrocarbons (alkanes, alkenes, alkynes) as background academic context rather than a clinical decision trigger.
Understanding the basic structure of hydrocarbons is foundational for pharmacology, as the carbon skeleton of many drugs determines their solubility, metabolism, and interaction with biological targets.
For example, many general anesthetics (e.g., halothane, isoflurane) are halogenated hydrocarbons, whose structures are related to simple alkanes.
What if? If the question asked for an aromatic hydrocarbon, a correct answer would be Benzene. The benzene ring is a core structure in many drugs, including aspirin and paracetamol.

How to Approach the Question

First, identify the key terms in the question: 'unsaturated hydrocarbon' and 'triple bond'.
Recall the nomenclature rules for hydrocarbons, where the suffix of the name indicates the type of carbon-carbon bond.
The suffix '-ane' signifies single bonds (alkanes, which are saturated).
The suffix '-ene' signifies at least one double bond (alkenes, which are unsaturated).
The suffix '-yne' signifies at least one triple bond (alkynes, which are unsaturated).
Examine the suffix of each option: Methane (-ane), Ethane (-ane), Propene (-ene), and Ethyne (-yne).

Concept Tested & Keywords

Concept Tested: Classification and nomenclature of hydrocarbons (alkanes, alkenes, alkynes).
Stem keywords: unsaturated hydrocarbons, triple bond
Lead-in keywords: Which
Negative lead-in flag: false

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Practise the full RRB Nsg. Superintendent - 29 April 2025 (Shift-3rd)

Attempt every question from this paper in a timed mock, then review the full solution for each one.