You notice that there are deposits of calcium carbonate (a hard, white substance) along the inside of the walls of the kiddie pool. what types of reaction caused this?

Calcium can build up in your pool water when the pH levels are off and leave deposits on your pool tiles. It's similar to what happens in your bathroom sink, toilet or bathtub.

More details:

There are two types of calcium compoundsthat form in pool water and create scaling--calcium carbonate and calcium silicate. Both are caused by a pH imbalance. Your pool should be at a pH between 7.4 and 7.6.

I hope this helps.

"d.) carbon dioxide and hydrogen sulfide"

chert is a sedimentary rock composed of microcrystalline or cryptocrystalline silica. with this little bit of information, you can come to the conclusion that your answer is c.  

explanation: