Out of the given options, the compound that is unsaturated is Methylbenzene. This is because the term "unsaturated" refers to a compound that contains at least one carbon-carbon double or triple bond. Methylbenzene, also known as toluene, has a double bond between one of its carbon atoms and the adjacent carbon atom in the benzene ring. Therefore, it is an unsaturated compound. The other options, 2-methylbutane, chloromethane, and 1,2-dibromoethane, are all saturated compounds as they contain only single bonds between their carbon atoms.