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प्रश्न
What is meant by (i) elements (ii) compounds, and (iii) mixtures ?Write down the names of two elements, two compounds and two mixtures.
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उत्तर
- Element: An element is a substance that cannot be split up into two or more simpler substances by chemical methods. It contains only one type of atoms. Examples of elements include:
- Non metals: Carbon and oxygen
- Metals: Aluminum, iron, copper, gold, mercury, and lead.
- Compound: A compound is a substance consisting of two or more elements combined chemically in a fixed proportion by mass.
Examples: Water, sodium chloride, calcium carbonate etc. - Mixture: – A mixture is a substance that is made up of two or more different kinds of particles or two or more pure substances mixed together by a physical process. Examples: Air, milk, wood, soil etc.
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संबंधित प्रश्न
Name the terms for the particles of matter which may or may not have independent existence.
Which of the following substances are elements ?
Water, Salt, Mercury, Iron, Marble, Diamond, Wood, Nitrogen, Air, Graphite, Hydrogen, Oxygen, Sugar, Chlorine
You have been given a suspension and a solution. How could you tell the difference between them by their appearance ?
What will happen if a saturated solution is :
- heated
- cooled
Which of the following are chemical changes and which physical ? Give reason.
- a glass bottle breaking
- coal burning in air
- making a cake
- wool being knitted into a sweater
Which of the following can be called a suspension ?
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 ?
Name the process by which common salt is purified.
Which technique can be used to detect and identify traces of poison present in the stomach wash of a person ?
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 will you separate a mixture containing sand and sugar ?
How will you separate a mixture of common salt, sulphur powder and sand ?
How will you separate water from mustard oil ?
How is cream separated from milk ?
Which method is better for recovering sugar from sugar solution : evaporation or crystallisation ? Give reason
for your answer.
How can you obtain pure water from a salt-water mixture (or salt-solution) ? Draw a neat and labelled diagram of the apparatus you would use to obtain pure water from a salt-water mixture (or salt-solution).
Which of the following are homogeneous in nature?
(i) ice
(ii) wood
(iii) soil
(iv) air
Solid is an arrangement of particles ______.
The movement of particles in liquids is ______.
Solids do not flow.
