Very Short Answers - Matter In Our Surroundings, Science, Class 9 PDF Download

Q1. Define matter.
Ans. Anything that occupies space and has mass is called matter.

Q2. State different states of matter with an example.
Ans. Matter has three different states

Q3. What is diffusion?
Ans. The intermingling of molecules of one substance with that of the other is called diffusion.

Q4. What happen to the rate of diffusion if the temperature is increased?
Ans. With increased temperature, the rate of diffusion also increases as the particles gain energy and vibrate more.

Q5. Name the state of matter that have the tendency to maintain their shape when subjected to outside force.
Ans. Solid.

Q6. Define melting point.
Ans. The minimum temperature at which a solid melts to become a liquid at the atmospheric pressure is called its melting point.

Q7. Define boiling point.
Ans. The temperature at which a liquid starts boiling at the atmospheric pressure is known as its boiling point.

Q8. Define latent heat of vaporization.
Ans. Latent heat of vaporization is the heat energy required to change 1 kg of a liquid to gas at atmospheric pressure at its boiling point.

Q9. Define latent heat of fusion.
Ans. Latent heat of fusion is the amount of heat energy required to change 1 kg of solid into liquid at atmospheric pressure at its melting point.

Q10. Define sublimation.
Ans. Sublimation is the change of gaseous state directly to solid state without going through liquid state.

Q11. What is dry ice?
Ans. Solid carbon dioxide obtained by cooling and applying pressure on carbon dioxide gas. It does not melt so it is called dry ice.

Q12. What is humidity?
Ans. The air holds water vapour, this air with water is called humid air and the amount of water vapour present in air is called humidity.

Q13. Give two properties of solid.
Ans. (1) Solids have fixed shape and are rigid. (2) Solids cannot be compressed.

Q14. What will happen if the pressure is reduced on solid carbon dioxide (dry ice)?
Ans. If the pressure is reduced on solid carbon dioxide it will directly change into gaseous state without melting.

Q15. Name any three substances that show sublimation.
Ans. Ammonium chloride, camphor and naphthalene balls.

Q16. Sponge is solid, but we can still compress it. Why?
Ans. Sponge is a solid with minute pores in it. When we press the sponge the air present in these pores is released out and hence we are able to compress it.

Q17. What is normal atmospheric pressure?
Ans. The atmospheric pressure at sea level is 1 atmosphere and taken as the normal atmospheric pressure.

Q18. What is Kelvin?
Ans. Kelvin is the SI unit of temperature (0°C = 273 K).

Q19. Give two examples of diffusion.
Ans. Milk drops dissolved in water and perfume sprayed in a room.

Q20. Give the temperature at which water exists in two different phases/states.
Ans. At 0°C water can be in solid or in liquid state. At 100°C water can be in liquid or in gaseous state