It can be anything with a big heat capacity like water
It has 6 electrons, and 4 valence electrons
This description applies and is suitable for what a chemical precipitate is. A precipitate is a product that is formed from a certain chemicals reaction that yields a solid that is insoluble in the reaction vessel. It is usually white and opaque.
Cellular respiration can be thought of as the opposite of photosynthesis. In cellular respiration oxygen is turned into carbon dioxide while in photosynthesis carbon dioxide is tuned to oxygen.
I hope this helps. let me know in the comments if anything is unclear.