Polluted Precipitation
This page is the CodyCross answer for the clue below from Science Lab, Group 307, Puzzle 5 (Combustion).
Question is: Polluted Precipitation
and the answer is: ACIDRAIN
Word Meaning:
ACID RAIN — Rain which is unusually acidic (pH of less than the natural range of 5 to 6); caused mainly by atmospheric pollution with sulphur dioxide, carbon dioxide and nitrogen compounds.
Definitions from Wiktionary.