Grade 7 Science Practice Test: Density and Properties of Matter

Density = mass / volume = 60 / 20 = 3 g/cm³. Multiplying gives 1,200, and dividing the wrong way gives about 0.33.

An object floats if it is less dense than the liquid. Only 0.8 g/cm³ is less than 1.0 g/cm³.

Cutting halves both the mass and the volume, so their ratio stays the same. Density depends on the material, not the size of the piece.

The stone's volume is 52 - 40 = 12 cm³, so density = 30 / 12 = 2.5 g/cm³. Using 52 mL or 40 mL as the volume gives the wrong values.

Density is a characteristic property: it is the same for any sample of a pure substance. Mass, volume and length depend on how big the piece is.

The least dense liquid floats on top and the densest sinks to the bottom. So oil is on top, then water, then honey.

57 / 6 = 9.5 g/cm³, which is about half the density of gold. Multiplying mass by volume gives the wrong value of 342.

Mass = density × volume = 2.7 × 50 = 135 g. Dividing 50 by 2.7 gives about 18.5, which is the wrong operation.

When water freezes, its particles lock into an open pattern that takes up more space. The same mass in a larger volume means lower density, so ice floats.

Heating makes the air particles move faster and spread out, so the same mass fills more volume. The less dense warm air is pushed up by the denser cool air around it.