Non-metals are generally solids and gases. Let's break down this answer in more detail:

What are non-metals?
Non-metals are a group of elements on the periodic table that do not have the characteristics of metals. They are typically poor conductors of heat and electricity, have low melting and boiling points, and are not malleable or ductile.

What states of matter do non-metals exist in?
Non-metals can exist in all three states of matter: solid, liquid, and gas. However, the majority of non-metals are solids at room temperature and atmospheric pressure. Some examples of solid non-metals include sulfur, carbon, and phosphorus.

On the other hand, some non-metals are gases at room temperature and atmospheric pressure. Examples of gaseous non-metals include oxygen, nitrogen, and chlorine. Additionally, a few non-metals can exist as liquids under certain conditions, such as bromine.

Why are non-metals generally solids and gases?
Non-metals tend to have weaker intermolecular forces compared to metals. This means that they have lower melting and boiling points, which allows them to exist as gases at lower temperatures than metals. Additionally, many non-metals have a low atomic mass, which makes it easier for them to exist as gases.

However, some non-metals are able to exist as solids due to their molecular structure and the strength of their intermolecular forces. For example, sulfur exists as a solid at room temperature and atmospheric pressure because its molecules form a cyclic structure that allows for stronger intermolecular forces.

In conclusion, non-metals can exist in all three states of matter, but they are generally solids and gases. This is due to their weaker intermolecular forces and lower atomic mass compared to metals.