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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
Which one is a kind of matter:
Which of the following materials fall in the category of a “pure substance”?
- Ice
- Milk
- Iron
- Hydrochloric Acid
- Calcium oxide
- Mercury
- Brick
- Wood
- Air
What are the characteristics of matter?
Which of the following is a mixture ?
Salt, Air, Water, Alum, Sugar
What is meant by saying that metals are malleable and ductile?
What is meant by saying that non-metals are brittle ?
Define a compound. Give two points of evidence to show that sodium chloride is a compound.
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 ?
A solution contains 5.6 mL of alcohol mixed with 75 mL of water. Calculate the concentration of this solution.
Choose one term from the following which includes the other three :
aerosol, emulsion, colloid, sol
State whether the following statement are true or false :
Alcohol can be separated from a mixture of alcohol and water by a separating funnel.
Fill in the following blanks with suitable words :
The separation of liquids by fractional distillation is based on the difference in their .....................
How is cream separated from milk ?
Explain how, impure copper sulphate can be purified by crystallisation.
Wipe the board with a duster and then tap the duster against the table. What do you see?
A standard sheet of paper is about ______ of atoms thick
You want to wear your favourite shirt to a party, but the problem is that it is still wet after a wash. What steps would you take to dry it faster?
Define the term matter.
Define the term matter.
Define the term matter.
