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प्रश्न
Define homologous series of organic compounds. List its two characteristics. Write the name and formula of the first member of the series of alkenes.
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उत्तर
A homologous series is a series of carbon compounds that have different number of carbon atoms but contain the same functional group.
For example, methane, ethane, propane, butane, etc. are all part of the alkane homologous series.
Methane CH4
Ethane CH3CH3
Propane CH3CH2CH3
Butane CH3CH2CH2CH3
There is a difference of −CH2 unit between each successive compound.
Characteristics of homologous series:
All the members of the homologous series have same functional groups and hence similar chemical properties.
Two successive members of a homologous series differ by a −CH2 unit and 14u.
The first member of the series of alkenes in ethene. Its formula is C2H4.
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संबंधित प्रश्न
What is meant by homologous series of carbon compounds?
Write the name and formula of the 2nd member of homologous series having general formula CnH2n + 2.
Propane and ethane are ______.
What is the difference in the molecular formula of any two adjacent homologues in terms of molecular mass?
Give three points to differentiate between saturated and unsaturated
hydrocarbons.
The phenomenon in which compounds having different structural formulae have the same molecular formula is called _______.
Complete the following table for the homologous series of alkanes.
| Name | Molecular formula | Condensed structural formula | Number of carbon atom | Number of -CH2- units | Boiling point °C |
| Methane | CH4 | CH4 | 1 | 1 | -162 |
| Ethane | C2H6 | CH3–CH3 | 2 | 2 | -88.5 |
| Propane | C3H8 | CH3–CH2–CH3 | 3 | 3 | -42 |
| Butane | C4H10 | CH3–CH2–CH2–CH3 | ______ | ______ | 0 |
| Pentane | C5H12 | CH3–CH2–CH2–CH2–CH3 | ______ | ______ | 36 |
| Hexane | C6H14 | CH3–CH2–CH2–CH2–CH2–CH3 | ______ | ______ | 69 |
What is called homologous series? Give any three of its characteristics?
Successive members of a homologous series vary by how many atomic mass unit?
Consider the carbon compounds having following molecular formula:
(i) C3H6 (ii) C3H8 (iii) C4H6 (iv) C6H6 (v) C6H12
- State the number of double covalent bonds present in C3H8.
- Write the formula of first member of the homologous series to which the carbon compound C4H6 belongs.
- Which one of the above compounds forms a ring structure of carbon atoms?
- Identify, which of the above compounds, is a member of alkane series.
