The mass per unit volume of a substance is called density.

Question 1. The mass per unit volume of a substance is called density. (Density = mass/volume).
Arrange the following in order of increasing density – air, exhaust from chimneys, honey, water, chalk, cotton and iron.
Answer: Arrangement of the above matters in order of increasing density
Air<exhaust from chimney<cotton<water<honey<chalk<Iron