Final answer:
Nitrogen gas (N2) is the compound among the given options that contains a triple bond, as the two nitrogen atoms share three pairs of electrons.
Step-by-step explanation:
The question seeks to identify which compound contains a triple bond. Among the given options, Nitrogen gas (N2) is the only compound with a triple bond. Each nitrogen atom has five valence electrons and they share three pairs to form a triple bond between them, making N2 a molecule with a triple bond. In contrast, ammonia (NH3) contains three single bonds and a lone pair, methane (CH4) has four single bonds, and chlorine (Cl2) consists of a single bond between two chlorine atoms.