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प्रश्न
What is meant by H20 and 3H2O
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उत्तर
H20 represents one molecule of water. 3H20 represents 3 molecules of water.
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संबंधित प्रश्न
Fill in the blank
A pure substance has definite.................. and constant ..............
Match the columns.
| column A | column B |
|
1. to separate grain from chaff |
a. filtration |
| 2. to saparate sawdust from water | b. sedimentation and deeantation |
| 3. to separate iodine from sodium chloride | c. winnowing |
| 4. to separate iron fillings from sand | d.sublimation |
|
5. it is used to separate sand and water |
e maganetic separation |
|
|
f .handpicking |
Differentiate between:
Homogenous and heterogenous substances
Fill in the blank
_________ refers to the number of atoms in the molecule of an element
Fill in the blank
The most abundant element in the atmosphere is _______.
Tick (√) the correct alternative from the choice given for the following statement
A metal which is brittle
The important physical properties of substances are colour, odour, nature, density & solubility in water.
Name – a gas with a pungent, choking odour which is lighter than air
Match the statements in List I – 1 to 10 correct answers in List II-A to J.
| List I | LIst II | ||
| 1 | Fluorine and chlorine | A | Nitrogen |
| 2 | A diatomic molecule | B | Boron |
| 3 | A molecule containing the elements hydrogen and oxygen. | C | Reactants |
| 4 | A metalloid - showing properties of both metals and non-metals. | D | Chemical Formula |
| 5 | The term used for the substances which take part in the chemical reaction | E | Halogens |
| 6 | The term represents a substance by means of symbols. | F | Water |
| 7 | The term used for the substances formed as a result of a chemical reaction | G | Nitric Acid |
| 8 | A compound containing one atom of zinc and two atoms of chlorine. | H | Products |
| 9 | The chemical name for nitrogen monoxide. | I | Phosphorus |
| 10 | A polyatomic molecule. | J | Zinc Chloride |
Non-metal conducting electricity :______ :: Metal conducting electricity : Copper
Assertion: Air is a mixture of elements only.
Reason: Only nitrogen, oxygen and neon gases exist in air.
