Which gas was not scheduled for phaseout by 1996 as noted in the Montreal Protocol?

The correct answer is that Halon was not scheduled for phaseout by 1996 as noted in the Montreal Protocol. The Montreal Protocol, which was ratified in 1987 and amended in subsequent years, aimed to phase out substances that deplete the ozone layer. Key types of substances targeted included chlorofluorocarbons (CFCs), carbon tetrachloride, and methyl chloroform, which were all included in the protocol's schedules for phaseout.

Halon, specifically used in fire suppression systems, was included in a later amendment and had specific deadlines for phaseout, which allowed its use to continue for certain applications beyond the 1996 deadline. Therefore, its regulation diverged from that of the other substances mentioned, which had more immediate deadlines for elimination. Understanding the context of this distinction is essential in recognizing the different categories of substances addressed by the Montreal Protocol and the varying timelines for their regulation.