Which of the following is necessary for a chemical to be considered a solvent?

For a chemical to be considered a solvent, it is essential that it can dissolve another substance. This fundamental property allows the solvent to interact with a solute, resulting in a homogeneous mixture known as a solution. The process of dissolving involves the breaking of intermolecular bonds in the solute and the surrounding solvent molecules, which then leads to the solute being evenly distributed throughout the solvent. This characteristic is why water, for example, is often referred to as the "universal solvent" due to its ability to dissolve many different substances.

In contrast, the other options do not fulfill the criteria for a substance to be classified purely as a solvent. While gases can act as solvents, especially in specific applications, being a gas is not a requirement. Forming a suspension refers to a mixture where solid particles are dispersed in a liquid; this does not characterize a solvent. Lastly, while some solvents can react chemically with solutes under certain conditions, a solvent does not need to partake in a chemical reaction to effectively dissolve a substance. Therefore, the ability to dissolve another substance is the defining characteristic that qualifies a chemical as a solvent.