Understanding Matter and Its Properties

Which of the following are matter? Chair, air, love, smell, hate, almonds, thought, cold, lemon water, smell of perfume.

• Chair, air, almonds, lemon water
• hate
• smell
• love

Give reasons for the following observation: The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close.

• The distance of smell is unrelated to temperature.
• The smell of hot sizzling food travels further because it releases more volatile aroma compounds compared to cold food.
• Hot food emits less aroma than cold food.
• Cold food has a stronger smell than hot food.

A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?

• Density of solids
• Viscosity of gases
• Fluidity of liquids
• Compressibility of solids

What are the characteristics of the particles of matter?

• Particles of matter are small, in constant motion, attract each other, and occupy space.
• Particles of matter do not occupy space.
• Particles of matter do not attract each other.
• Particles of matter are large and stationary.

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.

• air, exhaust from chimneys, cotton, water, honey, chalk, iron
• honey, water, chalk, cotton, exhaust from chimneys, air, iron
• iron, chalk, honey, water, cotton, exhaust from chimneys, air
• water, honey, air, exhaust from chimneys, cotton, chalk, iron

(a) Tabulate the differences in the characteristics of states of matter. (b) Comment upon the following: rigidity, compressibility, fluidity, filling a gas container, shape, kinetic energy and density.

• Rigidity: Solid (not rigid), Liquid (rigid), Gas (rigid)
• Compressibility: Solid (high), Liquid (low), Gas (low)
• 1. Rigidity: Solid (rigid), Liquid (not rigid), Gas (not rigid); 2. Compressibility: Solid (low), Liquid (moderate), Gas (high); 3. Fluidity: Solid (not fluid), Liquid (fluid), Gas (fluid); 4. Filling a gas container: Solid (no), Liquid (no), Gas (yes); 5. Shape: Solid (definite), Liquid (definite but takes the shape of the container), Gas (indefinite); 6. Kinetic Energy: Solid (low), Liquid (moderate), Gas (high); 7. Density: Solid (high), Liquid (moderate), Gas (low).
• Density: Solid (low), Liquid (high), Gas (moderate)

Give reasons (a) A gas fills completely the vessel in which it is kept. (b) A gas exerts pressure on the walls of the container. (c) A wooden table should be called a solid. (d) We can easily move our hand in air but to do the same through a solid block of wood we need a karate expert.

• A wooden table is a liquid.
• A gas does not fill the vessel completely.
• A gas does not exert pressure on the walls.
• A gas fills completely the vessel, exerts pressure, a wooden table is a solid, and moving through air is easier than through wood.

Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why.

• Ice is denser than liquid water.
• Ice floats on water because it is less dense than liquid water.
• Ice sinks because it is heavier than water.
• Ice has the same density as water.

Can Matter Change its State? We all know from our observation that water can exist in three states of matter – solid, as ice, liquid, as the familiar water, and gas, as water vapour. What happens inside the matter during this change of state? What happens to the particles of matter during the change of states? How does this change of state take place? We need answers to these questions, isn’t it?

• Yes, matter can change its state.
• No, matter cannot change its state.
• Matter can only exist in one state at a time.
• Matter changes state only under extreme conditions.

Can you define the latent heat of vaporisation? Do it in the same way as we have defined the latent heat of fusion.

• The latent heat of vaporisation is the energy released when a gas condenses into a liquid.
• The latent heat of vaporisation is the temperature at which a liquid boils.
• The latent heat of vaporisation is the heat required to freeze a liquid into a solid.
• The latent heat of vaporisation is the heat energy needed to convert a unit mass of liquid into vapor without a change in temperature.