Silver metal that is exposed to the air tarnishes and becomes doing black overtime this is most likely the result of

When silver is exposed to sulfur-containing gases in the air, it discolours and then darkens as it reacts with the gas to form a surface layer of tarnish. This process is called tarnishing, as explained below in The science of silver tarnish and its cause.

Explanation:

the pseudoscience are like beliefs, theories, or like practices that are considered scientific

qualitative observation deals with data that can be observed with our senses: sight, smell, touch, taste, and hearing. they do not involve measurements or numbers. for instance, colors, shapes, and textures of objects are all qualitative observations.