A precipitate(s), like a kidney stone, forms in a double-replacement reaction when

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

answer: cellular respiration takes in food and uses it to create atp, a chemical which the cell uses for energy. usually, this process uses oxygen, and is called aerobic respiration. it has four stages known as glycolysis, link reaction, the krebs cycle, and the electron transport chain.