Acid rain Rainwater has a pH of 5.7 if Co2 is the only species hat affects its acidity. When additional acidic species are present at appreciable levels as a result of man-made activities, pH of rain water becomes lower than 5.7.>Acid rain H2S04 and hno3 are the major contributors to acid rainAcid rain • Rainwater has a pH of 5.7 if CO2 is the only species that affects its acidity. • When additional acidic species are present at appreciable levels as a result of man-made activities, pH of rain water becomes lower than 5.7.→ Acid rain. • H2SO4 and HNO3 are the major contributors to acid rain