Step 1: Understanding Unsaturated Hydrocarbons
Unsaturated hydrocarbons are those that contain one or more double or triple bonds between carbon atoms. The most common unsaturated hydrocarbons are alkenes and alkynes.
Step 2: Explanation of Other Options
- (A) CH\(_4\) is methane, which is a saturated hydrocarbon (alkane).
- (C) C\(_3\)H\(_8\) is propane, another saturated hydrocarbon (alkane).
- (D) C\(_4\)H\(_{10}\) is butane, a saturated hydrocarbon (alkane).
Thus, the correct answer is (B) C\(_2\)H\(_4\), which is ethene, an unsaturated hydrocarbon.
