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प्रश्न
State three differences between water and air.
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उत्तर
Water:
- The components of water are hydrogen and oxygen which are chemically combined in a fixed ratio of 1 : 8 by mass.
- The chemical composition of water remains the same from whatever source it is obtained.
- The properties of water are completely different from the properties of elements from which it is formed i.e. hydrogen and oxygen.
- Energy change occurs in the formation of water.
- A molecule of water is represented by a definite formula H2O.
Air:
- The main components of air are nitrogen, oxygen, carbon -dioxide, water vapour which are not chemically combined.
- The composition of air varies from place to place. During the rainy season, the air becomes humid due to the presence of more water vapour. Some impurities like sulphur dioxide, hydrogen sulphide etc. also changes its composition at some places.
- The components of air retain their individual properties but not air.
- No energy change occurs when components of air are mixed together.
- Air cannot be represented by any chemical formula.
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संबंधित प्रश्न
Select the correct alternative from the choices given for the following statement:
A set of mixture is
The methods of separating components of a given mixture are based on the
Name the elements which form water.
How will you justify that water is a compound?
What is the proportion of element present in the following compound?
H2O
Name two compounds which dissolve in water.
Explain the term compounds.
Give the example of a compound containing hydrogen and oxygen.
Give the example of a compound containing nitrogen and oxygen.
Tabulate a comparative chart – to differentiate between elements, compounds, and mixtures. Differentiate them with reference to existence
What is the molecular formula of the following compound?
Sodium chloride
State true of false. If false, give the correct statement.
Compounds and elements are pure substances.
Write the chemical formula and name the elements present in the following compounds.
- Sodium chloride
- Potassium hydroxide
- Carbon dioxide
- Calcium oxide
- Sulphur dioxide
Assertion: Oxygen is a compound.
Reason: Oxygen cannot be broken down into anything simpler.
Match the following.
| Iron | For making wires |
| Copper | Sewing needle |
| Tungsten | As a fuel for ignition in rocket |
| Boron | Making the filament of a bulb |
Mention any four compounds and their uses.
State whether true or false. If false, correct the statement.
A compound cannot be broken into simpler substances chemically.
Reason out
Sand is also known as silica.
When does the pressure of the gas increase?
