## Class 9 - Physics

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#### 1. The Particles of Matter are Very, Very Small

The very, very small size of the particles of matter can be shown by performing the following experiment by using potassium permanganate and water. Potassium permanganate is a kind of matter. We take 2 or 3 small crystals of potassium permanganate and dissolve it in 100 millilitres (100 mL) of water in a beaker. We will get a deep purple coloured solution of potassium permanganate in water [see Figure 9(a)]. Take 10 mL of deep purple solution of potassium permanganate from the first beaker and mix it with 90 mL of water present in second beaker, to dilute it [see Figure 9(fr)J. Due to this dilution, the colour of potassium permanganate solution in the second beaker becomes a bit lighter. Now, take 10 mL of potassium permanganate solution from the second beaker and mix it with 90 mL of water present in the third beaker,to dilute it further [see Figure 9(c)]. The colour of solution will become still lighter. We keep on diluting the potassium permanganate solution like this a number of times (say, five times). In this way, we get a very dilute solution of potassium permanganate in water but the water is still coloured (it has a light pink colour now) [see Figure 9(f)].
This experiment shows that just 2 or 3 tiny crystals of potassium permanganate can impart colour to a large volume of water. From this observation we conclude that each potassium permanganate crystal itself must be made up of millions of small particles which keep on spreading and imparting colour to more and more of water (on dilution). Since each tiny crystal of potassium permanganate is supposed to be made up of millions of particles, therefore, these particles must by very, very small !.

## Notes

Sound - Notes
1. Effect of Change of Temperture
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2. 1. Temperature
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3. Effect of 'Heating' and 'Cooling' on a Saturated Solution
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4. 2. Liquid to Gas Change : Boiling (or Vaporisation)
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5. 4. Liquid to Solid Change : Freezing
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6. Two More States of Matter : Plasma and Bose-Einstein Condensate
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7. 2. Latent Heat of Vaporisation (Liquid to Gas Change)
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8. Effect of Change pressure
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9. 4. Wind Speed
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10. 1. Solid to Liquid Change : Melting
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11. Latent heat
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12. 2. Surface Area of the Liquid
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13. 3. Humidity of Air
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14. 4. The Particles of Matter Attract Each Other
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15. Diffusion in Liquids
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16. Evaporation
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17. Why Solids, Liquids and Gases Have Different Properties
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18. 1. Latent Heat of Fusion (Solid to Liquid Change)
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19. 2. The Particles of Matter have Spaces Between Them
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20. Properties of Solids
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21. 3. Gas to Liquid Change : Condensation
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22. Properties of Liquids
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23. Classification Of Matter As Solids, Liquids And Gases
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24. 3. The Particles of Matter are Constantly Moving
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25. 1. The Particles of Matter are Very, Very Small
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26. Change of State of matter
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27. Liquids
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28. Dissolving a Solid in a Liquid
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29. Gases
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30. Matter is made of particles
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31. Rigid and Fluid
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32. Factors Affecting Evaporation
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33. Diffusion
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34. Cooling Caused by Evaporation
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35. Solids
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36. Characteristics of Particles of Matter
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37. To Show That Solids and Liquids Cannot be Compressed but Gases Can be Compressed Easily
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38. The Common Unit Of Temperature and Si Unit Of Temperatre
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39. Mixing of Two Gases
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40. Sublimation
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41. Matter In Our Surroundings
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42. Evidence for Particles in Matter
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43. Movement of Pollen Grains in Water
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44. To Show that Liquids do not have a Fixed Shape but they have a Fixed Volume
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45. Gases Can be Liquefied by Applying Pressure and Lowering Temperature
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46. To Show the Presence of Water Vapour in Air
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47. To Show that Gases do not have a Fixed Shape or a Fixed Volume
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48. Diffusion in Solids
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49. Diffusion in Gases
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