What is a chemical weathering problem?

Answer 1

Acid rain, acid rain, acid rain . . . . . . . . .eats away at some stones and some (most) metals.

. . . and if you didn’t know, now you do . . .

Answer 2

Perhaps the elements of sleet, snow, rain, acid rain, exhaust fumes etc. and how something like aluminum siding would maintain its high quality finish.

But I'm not a chemist.