Cambridge Secondary (7-9). Stage 9. Science. Learner's Book - Unit 3: Forces and energy

Question 157

Which statements are true about the density of air? Give two letters.

The density of air is 0 g/cm³ because air has no mass.
The density of air is less than that of solids because the particles in air are further apart.
The density of air is more than that of liquids because the particles in air are closer together.
The density of air is more than that of a vacuum because a vacuum has no particles.