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प्रश्न
What are pure substances ? Give two examples of pure substances.
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उत्तर
Pure substances are made up of same type of particles or atoms. All the elements and compounds are pure substances because they contain the same kinds of particles.
Examples: Hydrogen, carbon dioxide
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संबंधित प्रश्न
Solids have definite shape and definite volume.
Differentiate between an atom and a molecule.
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.
When a crystal of potassium permanganate is placed in a beaker, its purple colour spreads throughout the water. What does this observation tell us about the nature of potassium permanganate and water?
Honey is more viscous than water. Can you suggest why?
Explain why air is used to inflate tyres.
Define a compound. Give two points of evidence to show that sodium chloride is a compound.
Classify the following into elements, compounds and mixtures :
arble, Air, Gold, Brass, Sand, Diamond, Graphite, Petroleum, Common salt, Sea-water, Chalk
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 ?
How will you differentiate between a suspension and a colloid ?
Define the emulsion. Give one example.
Name the process which can be used to purify an impure sample of copper sulphate.
What is chromatography ? State its two applications.
What is fractional distillation ? What is the use of fractionating column in fractional distillation ?
Justify your answer.
| Figure 1 | Figure 2 | Figure 3 |
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 |
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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?
Match the physical quantities given in column A to their S I units given in column B:
| (A) | (B) | ||
| (a) | Pressure | (i) | cubic metre |
| (b) | Temperature | (ii) | kilogram |
| (c) | Density | (iii) | pascal |
| (d) | Mass | (iv) | kelvin |
| (e) | Volume | (v) | kilogram per cubic metre |
Solids possess very high kinetic energy.
The physical state of water at 373 K is ______.
Higher the temperature, the higher the kinetic energy of particles.
