Is a measure of the quantity of matter in an object. volume mass density weight

*Warning* ( I'm not 100% sure) but I think it's mass xD

Answer is "mass" is a measure of quantity of matter in an object.

Explanation:

Let us define all the terms to have a better idea about the answer.

a) Volume : it is the measure of space occupied by an object. Volume is product of area and length. So if we keep an object, a solution, a substance etc, we measure volume to know how much space it is occupying. May be with that we can indirectly determine the amount, but not directly.

b) Mass : yes this is the measure of quantity of matter. a similar term "weight" is the measure of gravitational force on an object.

c) Density : it is the measure to know the amount of matter in a unit volume of an object.

d) weight : as defined, it is the measure of gravitational force on an object.

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.

it's c. elements are placed in rows based on how may valencies electrons have.