When you balance a chemical equation, what are you doing?

a. applying the law of conservation of energy

b. applying mendeleev's law

c. applying the law of conservation of matter

d. applying the periodic law

Answer is (C) - applying the law of conservation of matter .

Law of conservation of matter says matter can't be created or destroyed. Only thing can do is conservation.

Hence, in a chemical reaction, number of atoms of each element in reactants should be same as the number of atoms of each element in products.

the answer is:  

line graphs show patterns in data with variables that change over time; whereas, circle graphs show data as parts out of a whole (such as out of 100%).