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.


The order of densities is as follows 

Iron > Chalk > Honey > Water > Exhaust from chimneys > Air 


Explanation: We know that, 

Particles in solids are packed tightly

Particles in liquids are packed with some space between them

Particles in gases have more space between them.


So in a fixed volume, the number of particles would be greatest in solids, followed by liquids and then gases.


Density of solid > Density of liquid > Density of gas. 


Further, the arrangement of particles in different solids, liquids and gases are also different.

  1. Class 9
  2. Chapter 1 Class 9 - Matter In Our Surroundings

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.