Ozone gas in the stratosphere protects us from , but ozone gas in the troposphere is considered a and can be an irritant or cause someone with asthma to have an attack.

Acertain atom has 22 protons and 19 electrons. this atom loses an electron. the net charge on the atom is now 4+1+01-4-. if this same atom with 22 protons and 19 electrons were to gain 3 electrons, the net charge on the atom would be 3+2+02-3-.