Let us study some concepts in a Question And Answers way.
CBSE NCERT Book - Class 9th - Science - Chapter 1
MATTER IN OUR SURROUNDINGS
- What is a Matter?
Ans: Anything in this universe which occupies space and have mass is a Matter. In other words, they have both Volume and Mass.
- In Earlier times, Indian Philosophers classified Matters in the form of 5 basic elements. What are they?
Ans: Air, Earth, Fire, Sky and Water. They are also known as "Panch Tatva".
- What are the Characteristics of "Particles of Matter"?
Ans:
- Particles of Matter have space in between them.
- Particles of Matter are continuously moving.
- Particles of Matter attract each other
- What is Diffusion?
Ans: Intermixing of Particles of two different types of matter on their own is called diffusion. Example - Diffusion of Ink with Water in the glass. Diffusion of Potassium Permanganate crystal in a glass of hot water.
- On Heating, Kinetic Energy of particles?
Ans: On Heating, Kinetic Energy of particles increases. This is because, Particles of matter are continuously moving and they possess Kinetic Energy. As the temperature rises, particles move faster. Thus we can conclude that with increase in temperature, kinetic energy of particle also increases.
- What are the 3 different states of Matter? Give basic Difference.
Ans:
- Solid - Fixed Shape, Fixed Volume
- Liquid - No fixed Shape, but have Fixed Volume.
- Gas - No fixed Shape, No fixed Volume
- Arrange the states of Matter in the order of higher diffusion rate to lower diffusion.
Ans: (Higher Diffusion) Gas > Liquid > Solid (Low Diffusion rate)
- When a solid melts, why does its temperature remain the same?
Ans: When the ice melts, temperature of the system does not change till the melting point is reached. This happens because when we continue to supply heat, the heat gets used up in changing the state of matter by overcoming the forces of attraction between the particles. The heat energy is getting absorbed by ice and its known as latent heat since it is hidden into the content of the beaker.
- What is a Melting Point?
Ans: The minimum temperature at which a solid melts to become a liquid at the atmospheric pressure is called its Melting point.
Example - Melting point of Ice is 273.15 K (K - Kelvin).
- What is Latent Heat of Fusion?
Ans: Amount of heat energy that is required to change 1 Kg of a solid into liquid at atmospheric pressure at its melting point is called as its latent heat of fusion.
- What is Boiling Point?
Ans: The temperature at which liquid starts boiling at atmospheric pressure is known as boiling point.
- What is Latent heat of vaporisation?
Ans: Amount of heat energy that is required to change 1 Kg of liquid into gas at atmospheric pressure at its boiling point is called as its latent heat of vaporisation.
- What is Sublimation?
Ans: A change of state directly from solid to gas without changing into liquid state is known as sublimation.
Example - Sublimation of Ammonium Chloride on being heated.
- What is Deposition?
Ans: Direct change of gas to solid without changing into Liquid is called deposition.
- How can we liquefy gases?
Ans: Gases can be liquefied by applying pressure and reducing temperature.
- What is Evaporation?
Ans: Phenomenon of change of a Liquid into vapours at any temperature below its boiling point is called Evaporation.
- What are the factors affecting Evaporation?
Ans: Rate of Evaporation increases with:
- Increase in Surface area.
- Increase of temperature.
- Decrease in Humidity.
- Increase in Wind temperature.
- How does evaporation cause cooling?
Ans: When in an open vessel, water keeps evaporating. During this process, the particles of Liquid absorb energy from the surrounding to regain the energy lost during evaporation. This absorption of energy from the surrounding area makes the surroundings cool.
