The respiratory system works with the circulatory system to provide this oxygen and to remove the waste products of metabolism. It also helps to regulate pH of the blood. Respiration is the sequence of events that results in the exchange of oxygen and carbon dioxide between the atmosphere and the body cells.
Atomic mass number is the number of protons and neutrons. Subtract 80-35=45 is the number of protons. Because the atom is neutrally charged, the number of protons must equal the number of electrons, so there are 45 electrons.
A weirdly worded question. That chemical formula is of glucose which is a carbohydrate as it consists of carbon, oxygen and hydrogen atoms and is a monosaccharide (simple sugar). It had 6 carbon atoms