Rainwater is slightly acidic. why?

rainfall is slightly acidic because of the presence of dissolved carbonic acid ... The gases of sulfur oxides and nitrogen oxides are chemically converted into sulfuric and nitric acids.

Rainwater is slightly acidic because ... Water reacts with carbon dioxide to form carbonic acid. Due to high carbon dioxide emission in oceans, it explains why sea waters are acidic. Carbonic acid then breaks down into hydrogen ions and hydro carbonates ions. The hydrogen ion raises the water pH and, thus, causes the rainwater to be slightly acidic.