Complete the following sentences about the effect of pollutants released when coal is burned.

Apart from being pollutants on their own, 1. ___ have at least two major effects on the atmosphere. First, when they react with water vapor and oxygen, they produce nitric acid, causing acid rain. Further, their reactions produce 2. ___ in the lower atmosphere.

1.
a) nitrogen oxides
b) oxides of carbon
c) methane and ethane

2.
a) sulfur dioxide
b) ozone
c) carbon monoxide