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प्रश्न
Name the scientist who studied the movement of pollen grains suspended in water through a microscope. What is this phenomenon known as?
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उत्तर
Robert Brown studied the movement of pollen grains suspended in water through a microscope. He observed that the pollen grains moved in a zigzag motion. This phenomenon is called Brownian motion and it provides an evidence for existence and movement of particles.
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संबंधित प्रश्न
Match the following
| Column A | Column B | ||
| (a) | Molecules | (i) | Water boils |
| (b) | 100° C | (ii) | Evaporation |
| (c) | 0° C | (iii) | Changes from solid to gas |
| (d) | At all temperatures | (iv) | Matter |
| (e) | Camphor | (v) | Water freezes |
Give one difference between atoms and molecules.
Write true or false for each statement. Rewrite the false statement correctly.
Matter cannot exist in different states.
Name two processes which provide the best evidence for the motion of particles in matter.
What is Brownian motion? Draw a diagram to show the movement of a particle (like a pollen grain during Brownian motion.
You are given two liquids, one a solution and the other a compound. How will you distinguish the solution from the compound ?
Which of the following are not compounds ?
Chlorine gas, Potassium chloride, Iron powder, Iron sulphide, Aluminium foil, Iodine vapour, Graphite, Carbon monoxide, Sulphur powder, Diamond
Draw a flow-chart for the schematic representation of different types of matter.
A, B and C are all liquids. Liquid A has a comparatively low boiling point. On heating, liquid A vaporises completely without leaving behind any residue. Liquid A is being used increasingly as a fuel in motor vehicles either alone or by mixing with petrol. Liquid B has a very high boiling point. It also vaporises completely on heating, without leaving any residue. Liquid B is a conductor of electricity and used in making thermometers. Liquid C has a moderate boiling point. On heating, liquid C vaporises leaving behind a white solid D which is used in cooking vegetables. The condensation of vapours from C give a liquid E which turns anhydrous CuSO4 to blue.
(a) Which liquid could be an element ? Name this element.
(b) Which liquid could be a mixture ? Name this mixture.
(c) Which liquid could be a compound ? Name this compound.
(d) What could the solid D be ?
(e) What do you think is liquid E ?
What happens when the temperature of a saturated sugar solution is increased ?
Which of the following contains less solute at a given temperature and pressure ? Unsaturated solution or Saturated solution.
Which of the following represents the solubility of sugar in water at 20°C ?
What difference in the property of two miscible liquids enables their separation by fractional distillation ?
Fill in the following blanks with suitable words :
A mixture of kerosene and petrol can be separated by .....................
The liquid air has three components X, Y and Z whose boiling points are : –186°C, –183°C and –196°C,
respectively. When liquid air is fed into a tall fractional distillation column from near its bottom and warmed
up slowly :
(a) Which component will be collected from near the bottom of the fraction distillation column ? Why ?
(b) Which component will be collected from the top part of the fractional distillation column ? Why ?
(c) Which component will be collected from the middle part of the fractional distillation column ? Why ?
(d) What could the component X, Y and Z be ?
What difference in the properties of common salt and sand would enable you to separate a mixture of these two substances ?
Explain the meaning of the term matter with special reference to the term ‘substance’.
Justify your answer.
| Figure 1 | Figure 2 | Figure 3 |
 |
 |
 |
The arrangement of particles in three different phases of matter is shown above.
- Which state is represented by Fig. 1?
- In which state will the inter-particle attraction be maximum?
- Which one of them cannot be contained in an open vessel?
- Which one can take the shape of its container?
Which of the following are homogeneous in nature?
(i) ice
(ii) wood
(iii) soil
(iv) air
Liquids cannot be compressed and they have fixed volume.
