Which substance would have a higher specific gravity than water?

Specific gravity is defined as the ratio of the density of a substance to the density of water at a specified temperature (usually 4 degrees Celsius, where water is densest). Since water has a specific gravity of 1, any substance with a specific gravity greater than 1 is denser than water.

Chlorine gas, in its liquid form, is denser than water, with a specific gravity greater than 1. This means that when chlorine gas is cooled to a liquid state, it becomes denser than water, and thus it possesses a higher specific gravity.

In contrast, pure water has a specific gravity of 1, and gases like oxygen and hydrogen have significantly lower densities than water, resulting in specific gravities less than 1. Thus, chlorine gas in its liquid form is the only choice among the options that can be said to have a higher specific gravity than water.