Acid rains are produced by:

When fossil fuel burnt in automobile engines different oxides like NO, NO2, SO2, SO3 are produced. In the presence of moisture these oxides convert in the acids. These acids come down from the atmosphere in the form of rain, called acid rain.S from fossil fuel + O2 →  SO2 SO2 + O3 →  SO3 + O2 SO2 + H2O2 →  H2SO4 SO3 + H2O →  H2SO4 2NO2 + H2O →  HNO3 + HNO2