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प्रश्न
Explain why, hydrogen and oxygen are considered elements whereas water is not considered an element.
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उत्तर
Hydrogen and oxygen are considered as elements because they cannot be split further into simpler substances by usual chemical methods as they are made of one kind of atoms. On the other hand, water is not an element, as it consists of different types of atoms, i.e., hydrogen and oxygen and can be split up into its components by chemical processes.
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संबंधित प्रश्न
Fill in the blank :
The state of matter with definite volume and definite shape is called______
Write true or false for each statement. Rewrite the false statement correctly.
Matter cannot exist in different states.
Which of the following materials fall in the category of a “pure substance”?
- Ice
- Milk
- Iron
- Hydrochloric Acid
- Calcium oxide
- Mercury
- Brick
- Wood
- Air
Classify the following into elements, compounds and mixtures:
- Sodium
- Soil
- Sugar solution
- Silver
- Calcium carbonate
- Tin
- Silicon
- Coal
- Air
- Soap
- Methane
- Carbon dioxide
- Blood
In the following set of substances, one item does not belong to the set. Select this item and explain why it does not belong to the set :
Hydrogen, Oxygen, Steam, Chlorine
Calculate the concentration of a solution which contains 2.5 g of salt dissolved in 50 g of water.
Fill in the following blank :
Milk is a .................... solution but vinegar is a .................... solution.
Fill in the following blank :
A colloid is a ..............mixture and its components can be separated by the technique known as ...............
In what respects does a true solution differ from a colloidal solution ?
Define Aerosol Give one example.
Fill in the following blanks with suitable words :
The separation of liquids by fractional distillation is based on the difference in their .....................
Fill in the following blanks with suitable words :
If a mixture contains iron filings as one of the constituents, it can be separated by using a .......................
How would you obtain sodium chloride from a mixture of sodium chloride and sulphur without using water ?
Describe a method for separating a mixture of iron filings and sulphur powder other than that by using a magnet.
What is chromatography ? State its two applications.
How is water purified on a large scale at water works ? Explain with the help of a labelled diagram. Name the substance which is added to kill germs in the drinking water supply ?
Tincture of iodine is a mixture of two materials X and Y. The material Y has a property that its solid form can be converted directly into vapours on heating by a process called Z.
- What could X be ?
- What could Y be ?
- Name the process Z.
- Which process would you use to recover both the components X and Y from tincture of iodine ?
- Which process can be used to recover only component Y from tincture of iodine ?
Why wires cannot be drawn from materials such as stone or wood?
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 |
Define the term matter.
