If you cut the amount of matter in half, which property would halve?

• A. Mass
• B. Colour
• C. Volume
• D. Density

Answer: (A)

The amount of matter directly determines how much stuff there is, which is mass. If you cut the amount of matter in half, the mass becomes half because mass is a measure of the quantity of matter itself. Colour doesn’t depend on how much material you have, so it would stay the same. Volume and density are related through mass, but halving the amount of matter doesn’t automatically make density halve, since volume could change in response as well. So the property that necessarily halves when you reduce the amount of matter is mass.