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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
Fill in the blank :
The substances which can flow are called ________
All kinds of matter
Fill in the following blank with suitable words :
The best evidence that the particles of matter are constantly moving comes from the studies of ................. and ...................
What name is given to those elements which are neither good conductors of electricity like copper nor insulators like sulphur ?
The three important metalloids are.............................. and ..........................
Classify the following into elements and compounds :
- H2O
- He
- Cl2
- CO
- Co
What are pure substances ? Give two examples of pure substances.
State one property in which a solution of sugar in water resembles a mixture of sugar and sand, and one property in which it differs from it.
Name a metal which is yellow in colour.
What are (i) metals (ii) non-metals, and (iii) metalloids ? Give two examples each of metals, non-metals and metalloids.
There is a large group of materials P which can be divided into three groups Q, R and S on the basis of their properties. The substances belonging to group Q can be solids, liquids or gases. The solids belonging to group Q are usually electrical insulators. Most of the substances of group R are solids which are good conductors of electricity. The substances belonging to group S are neither insulators like Q nor good conductors like R. The properties of S are intermediate between those of Q and R.
- What could the group of materials P be ?
- Name the substances Q. Give two examples of such substances.
- Name the substances R. Write two examples of such substances.
- Name the substances S. Give two examples of such substances.
- Out of Q, R and S, which substances are malleable and ductile ?
What is the difference between solutions and colloids ?
Define Sol and give one example.
What is meant by the concentration of a solution ?
Milk of Magnesia is :
What is the difference between colloids and suspensions ?
Name the process by which common salt is obtained from sea-water.
Which of the following are homogeneous in nature?
(i) ice
(ii) wood
(iii) soil
(iv) air
The movement of particles in liquids is ______.
______ is used for industrial refrigeration and transporting frozen food.
