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प्रश्न
What is a homologous series? Explain with an example.
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उत्तर
- A group of compounds having similar structures and chemical properties but their successive compounds differ by a CH2 group is called a homologous series.
- Example: Alkanes have similar structures and similar chemical properties, so they can be grouped together to form a homologous series. The general formula of the homologous series of alkanes is CnH2n+2, where n is the number of carbon atoms in each molecule.
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संबंधित प्रश्न
Write the name and formula of the 2nd member of homologous series having general formula CnH2n – 2.
Write the molecular formula of first two members of homologous series having functional group – OH
Complete the following table which relates to the homologous series of hydrocarbons.
|
General Formula |
IUPAC name of the homologous series | Characteristic bond type | IUPAC name of the first member of the series |
| `C_nH_(2n-2)` | (A)________ | (B)______ | (C)______ |
| C_nH_(2n+1) | (B)________ | (E)______ | (F)______ |
What is the next higher homologue of methanol (CH3OH)?
The molecular formula of an organic compound is C18H36. Name its homologous series.
The number of carbon atoms present in the molecule of fifth member of the homologous series of alkynes is:
(a) four
(b) five
(c) six
(d) seven
An organic compound having the molecular formula C3H6O can exist in the form of two isomers A and B having different functional groups. The isomer A is a liquid which is used as a solvent for nail polish. The isomer B is also a liquid. An aqueous solution of one of the lower homologues of B is used for preserving biological specimens in the laboratory
(a) What is compound A?
(b) Write the electron-dot structure of A.
(c) What is compound B?
(d) Write the electron-dot structure of B.
(e) Name the lower homologue of compound B which is used in preserving biological specimens.
Define homologous series of organic compounds. List its two characteristics. Write the name and formula of the first member of the series of alkenes.
Distinguish between homologous organs and analogous organs. In which category would you place wings of a bird and wings of a bat? Justify your answer giving a suitable reason.
Complete the correlation:
Alkene : C = C :: Alkyne: _______.
The phenomenon in which compounds having different structural formulae have the same molecular formula is called _______.
Saturated hydrocarbon : Single bond : : Unsaturated hydrocarbon : _______
Complete the following table for homologous series of Alkenes.
| Name | Molecular formula | Condensed structural formula | Number of carbon atom | Number of -CH2- units | Boiling point °C |
| Ethene | C2H4 | CH2 = CH2 | 2 | 0 | -102 |
| Propene | C3H6 | CH3–CH = CH2 | 3 | 1 | -48 |
| 1-Butene | C4H8 | CH3–CH2–CH = CH2 | ______ | ______ | -6.5 |
| 1-Pentene | C5H10 | CH3–CH2–CH2–CH = CH2 | ______ | ______ | 30 |
Which of the following pairs can be the successive members of a homologous series?
What is called homologous series? Give any three of its characteristics?
C3H8 belongs to the homologous series of ______.
Which of the following does not belong to the same homologous series?
Name the third homologue of alcohols.
Name the third homologue of aldehydes.
