An example of highly unsaturated hydrocarbon is

To determine a highly unsaturated hydrocarbon, we must first understand the concept of saturation in hydrocarbons. **Saturated hydrocarbons** are compounds that contain the maximum possible number of hydrogen atoms, single-bonded to carbon atoms, and they are alkanes. **Unsaturated hydrocarbons** have one or more double or triple bonds between carbon atoms, which reduces the number of hydrogen atoms that can be bonded.

Examining the given options:

• C₂H₂ - also known as ethyne (or acetylene), has one carbon-carbon triple bond. A triple bond means it is highly unsaturated because it reduces the number of hydrogen atoms per carbon.
• CH₄ - known as methane, is a saturated hydrocarbon with single bonds only.
• C₂H₄ - known as ethene (or ethylene), has one carbon-carbon double bond, making it unsaturated.
• C₄H₁₀ - known as butane or isobutane, is another saturated hydrocarbon with single bonds only.

Based on this analysis, **C₂H₂** (ethyne) is a highly unsaturated hydrocarbon due to the presence of a **triple bond**. The triple bond signifies a greater level of unsaturation compared to double bonds in hydrocarbons like ethene (C₂H₄).