Class 9 - Chemistry
Explain why, ice at 0°C is more effective in cooling than water at the same temperature.
Questions and Answers
Matter in Our Surroundings - Questions
1. 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.
2. What is the physical state of water at the following temperatures? (a) 25 °C (b) 0 °C (c) 100 °C
3. What are the differences between boiling and evaporation?
4. Convert the following temperatures:
a. -78.0 °C to Kelvins
b. 775 K to °C
c. 489 K to °C
d. 24 °C to kelvins
5. What causes evaporation?
Explain evaporation and its cooling effect in terms of kinetic energy of particles.
6. Why does steam cause more severe burns than boiling water, though both are at the same temperature?
7. Give reasons for the following observations. The smell of hot sizzling food reaches you several meters away, but to get smell from cold food you have to go close.
8. Convert the following temperature to Celsius scale: (a) 300 K (b) 573 K
Draw a diagram to show interconversion among states of matter.
10. A diver is able to cut through water in a swimming pool. Which property of matter does this observation show?
11. Which of the following state does not exist at room temperature conditions: a) Solids b) Liquids c) Gas d) Plasma
State True or False:
a. Evaporation of water is a bulk phenomenon.
b. Diffusion takes place in haphazard and random way.
c. SI unit of pressure is Pascal.
d. A gas is highly incompressible fluid.
e. Solids and liquids can be identified from their characteristic melting and boiling points.
Fill in the blanks:
a. The process of ________ causes cooling.
b. The process of cooling glass is known as ____.
c. Liquids have no fixed ______ but have fixed _____.
d. ____ exists in all three states of matter.
e. Carbon dioxide is a white solid called _____ at temperature below ______.
14. What are the characteristics of matter?
15. Which of the following are matter?
Chair, Air, Love, Smell, Hate, Almonds, Thought, Cold, Cold drinks, Smell of perfume
16. What is SI unit of temperature? Give mathematical relation also.
17. Define transpiration.
18. List any five physical properties of liquids.
19. Why is light not considered matter?
20. How heat is transferred when a solid sublimes?
21. 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.
23. What do you mean by the term Volume?
24. What do you mean by the following terms:
25. Define Latent Heat of Fusion and Latent Heat of vaporisation.
26. Define the term Volatile Liquid.
27. Arrange the following substances in increasing order of intermolecular force of attraction: water, sugar, oxygen
28. Why do diffusion become faster at higher temperatures?
29. Define boiling. Why boiling is considered as a bulk phenomenon?
30. What is evaporation? Why does evaporation cause cooling?
31. In which case evaporation of water will be faster i.e. near the sea or far away from the sea.
32. Why is ice at 273 K more effective in cooling than water at the same temperature?
33. What are the ways a gas can be liquefied?
34. What is a dry ice and what are its properties?
35. How vapour is different from gases? Give examples of each.
36. Why do solids expand a bit on heating and contract a bit on cooling?
What are different physical states of matter? Name their properties as well?
38. Explain compressibility in gases with an example?
39. What do you mean by change in state?
40. Give reasons to justify: (a) Water at room temperature is a liquid. (b) An iron almirah is solid.
Why does the temperature of a substance remain constant during melting and boiling even when heat is being supplied to it continuously?
Differences among solids, liquids and gases.
Name matter classification in terms of composition.
45. After rains when do rain drops dry away easily– on a cloudy day or on a sunny day? State reason also.
46. Our own bodies contain examples of all three states of matter. Can you identify these?
47. How can matter change its state?
48. What factors affect the rate of evaporation?
49. Why solids cannot be compressed like gases?
50. How matter is classified in terms of physical state?
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