The kidneys and sweat glands both work to prevent excesses of either uric acid or urine in the body. either water or salt in the body. either carbon dioxide or oxygen in the body. either feces or ph levels in the body.

Either water or salt in the body

Explanation:

Function of kidneys is to produce the concentration or dilute urine according to the hydration level of body as well as to maintain the electrolyte level (level of Na, K, calcium and bicarbonate ions) of blood.  Similarly, sweat glands serve to maintain the water-salt level of body by release of excess water and salt from the body in form of sweat.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.