Answer:
27) Double replacement
28) 2NaOH + H2SO4 --> Na2SO4 + 2H2O
Answer;
it combines with the water and H in the atmosphere and creates sulfuric acid thus making the rain acidic
Explanation:
There are many combinations because it is not all about the number of chemicals, but also about the size of the strand. The longer the strand the more combinations there are and more variations and various lengths provide various results.
