These chemical compounds are all related to carbonate salts and carbon dioxide.

KOH - Potassium hydroxide, a strong base commonly used in industry and laboratories
KHCO3 - Potassium bicarbonate, a chemical compound used in food and pharmaceutical industries
K2CO3 - Potassium carbonate, a white salt used in fertilizers, soaps, and glass manufacturing
CO2 - Carbon dioxide, a gas that is essential for photosynthesis in plants and is a byproduct of combustion processes
CaCO3 - Calcium carbonate, a common mineral found in rocks, shells, and the human body
Ca(HCO3)2 - Calcium bicarbonate, a soluble form of calcium found in mineral waters.