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प्रश्न
Explain why steel is used to make railway lines.
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उत्तर
Steel is used to make railway lines because the particles of steel have fixed positions and show no free movement. This ensures that there will be no change in the shape of the railway lines, which makes it safe to travel.
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संबंधित प्रश्न
Liquids have definite volume but do not have definite shape.
Name two processes which provide the best evidence for the motion of particles in matter.
What are the characteristics of matter?
When extremely small particles X derived from the anther of a flower were suspended in a liquid Y and observed through a microscope, it was found that the particles X were moving throughout the liquid Y in a very zig-zag way. It was also observed that warmer the liquid Y, faster the particles X moved on its surface.
- What could particles X be ?
- What do you think liquid Y is ?
- What is the zig-zag movement of X known as ?
- What is causing the zig-zag movement of particles X ?
- Name the scientist who discovered this phenomenon.
- What does this experiment tell us about the nature of liquid Y?
Name a metal which is soft and a non-metal which is hard.
Which of the following substances are elements ?
Water, Salt, Mercury, Iron, Marble, Diamond, Wood, Nitrogen, Air, Graphite, Hydrogen, Oxygen, Sugar, Chlorine
Define a compound. Give two points of evidence to show that sodium chloride is a compound.
What are (i) metals (ii) non-metals, and (iii) metalloids ? Give two examples each of metals, non-metals and metalloids.
The element which is not common between the compounds called baking soda and soda ash is
Calculate the concentration of a solution which contains 2.5 g of salt dissolved in 50 g of water.
The solubility of ammonium chloride in water at various temperatures is given below :
| Temperature | : | 10°C | 20°C | 40°C | 60°C | 80°C |
| Solubility | : | 24 g | 37 g | 41 g | 55 g | 66 g |
What mass of ammonium chloride would be needed to make a saturated solution of ammonium chloride in fifty grams of water at 40°C ?
How will you separate a mixture of iron filings and powdered carbon ?
Describe the method of separating a mixture containing common salt, sand and ammonium chloride.
What is chromatography ? State its two applications.
The dyes present in fountain pen ink can be separated by the technique of :
Pure copper sulphate can be obtained from an impure sample by the process of :
Diffentiate between absorption and adsorption.
The non S I and S I units of some physical quantities are given in column A and column B respectively. Match the units belonging to the same physical quantity:
| (A) | (B) | ||
| (a) | degree celsius | (i) | kilogram |
| (b) | centimetre | (ii) | pascal |
| (c) | gram per centimetre cube | (iii) | metre |
| (d) | bar | (iv) | kelvin |
| (e) | milligram | (v) | kilogram per metre cube |
Non-metals are usually poor conductors of heat and electricity. They are non-lustrous, non-sonorous, non-malleable and are coloured.
Name a non-metal which exists as a liquid at room temperature.
The physical state of water at 373 K is ______.
