What is Molecule ?
What is Molecule :-
- Generally molecule is a group of two or more atoms which are joined together by chemical bonds, which cannot be separated by general physical methods.
- Therefore, the minutest particle of an element or compound which can exist independently and expresses all the characteristic properties of that compound, is termed as a molecule. For example : molecules of salt, molecules of phosphorus etc.
Important Points :-
- 1. Water, Air, Stone – all are matter.
- 2. There are primarily three physical states of matter – solid, liquid and gas.
- 3. The information regarding atom was first of all given by Maharshi Kanad.
- 4. Atomism was given by John Dalton.
- 5. Molecules are formed by chemical combination of atoms in a definite proportion.
- 6. Matter is present in the form of element, compound and mixture.
- 7. There are two type of molecules – elemental and compounds.
- 8. Mixture is formed by combining matter in indeterminate or definite proportions.
- 9. Conversion of ice into water is a physical change while breaking of ice molecules into hydrogen (H2 ) and oxygen (O2 ) is a chemical change.
- 10. The matter can be purified by crystallisation, distillation, fractional distillation, differential extraction, filteration etc.
Molecule Questions-Answers
Q. 1 When did Maharshi Kanad provided information regarding atom?
(a) 500 BC
(b) 100 BC
(c) 460 BC
(d) 1808 AD
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Q. 2 The atomicity of oxygen in ozone is :
(a) 1
(b) 2
(c) 3
(d) 4
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Q. 3 Which of the following substance is not solid at room temperature ?
(a) Salt
(b) Alum
(c) Oxygen
(d) Sal ammoniac
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Q. 4 The temperature at which liquid changes to solid is known as :
(a) melting point
(b) boiling point
(c) freezing point
(d) condensation temperature
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Q. 5 Which of the following options, is a mixture?
(a) Water
(b) Brass
(c) Iron
(d) Salt
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