Fill in the following blanks with suitable words:(a) In water, the proportion of oxygen and hydrogen is _ by mass.(b) In a chemical reaction, the sum of the masses of the reactants and the products remains unchanged. This is called _.

(a) In water, the proportion of oxygen and hydrogen is 1:8 by mass.

(b) In a chemical reaction, the sum of the masses of the reactants and the products remains unchanged. This is called Conservation of Mass.