NCERT Solutions for Class 9th Science
Chapter 1. Matter in Our Surroundings
Que. – What are the characteristics of the particles of matter ?
Ans. - The characteristics of the particles of matter are the following.
- Particles of matter have space between them.
- Particles of matter are continuously moving.
- Particles of matter attract each other.
Que. – Write three physical state of matter.
Ans. - (i) solid
Que. – What is Evaporation?
Ans. – The phenomenon of change of a liquid into vapours at any temperature below its boiling point is called evaporation.
Que. – Give the reason for the smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close.
Ans. – It is the property of matter that increasing the temperature, the particles of matter spread very faster. Thus the smell of hot food spread faster than cool food.
Que. – A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
Ans. – This observation shows that there is space between water molecules (particles of matter).
Que. – What is Fusion?
Ans – The process by which a solid get converted into liquid is known as fusion.
Que. – What is Solidification?
Ane. – The process by which a liquid get converted into solid is known as solidification.
Que. – What is sublimation?
Ane. – The process by which a solid get converted into gas directly without being converted into its liquid form is known as sublimation.
Que. – What is deffusion?
Ans. – Intermixing of particles of two different types of matter on their own is called diffusion.
Que – Write one factor which influence diffusion.
Ans – Heat.
Que. – Why is the rate of diffusion of liquids is higher than that of the solids?
Ans. – This is due to the fact that in the liquid state, particles move freely and have greater space between each other as compared to particles in the solid state.
Que – Write the factors which influence the rate of evaporation.
Ans – There are four factors which influence the rate of evaporation.
- An increase of surface area.
- An increase of temperature
- A decrease in humidity.
- An increase in wind speed
Que – Write the property of solid liquid and gas .
- Solid have a definite shape.
- Solid have a fixed volume.
- It cannot be changed its shape.
- Inter molecular force are strongest in solid.
- Liquids have no fixed shape.
- Liquids flow and change shape so they are not rigid.
- They are not compressed.
- Inter molecular force are less strong in liquids.
- Gases neither have a definite.
- They can do compressed.
- Gas can also flow.
- Inter molecular force are large space than solid and liquid.