Why can humans not see ultraviolet (UV) light?

Most humans cannot see ultraviolet light because it has a smaller wavelength than violet light, putting it outside of the visible spectrum.

equal distribution i think.

in a chemical reaction, the atoms and molecules produced by the reaction are called products. no new atoms are created, and no atoms are destroyed. in a chemical reaction, reactants contact each other, bonds between atoms in the reactants are broken, and atoms rearrange and form new bonds to make the products.