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प्रश्न
State any four characteristics of a homologous series
State two characteristics of a homologous series.
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उत्तर
Characteristics of a homologous series:
- Each member of the series differs from the preceding one by the addition of a -CH2 group and by 14 a.m.u.
- All members of a homologous series share the general formula.
Example: The general formula for alkane is CnH2n+2 and alkene is CnH2n. - The physical properties of the members show a gradation in properties as the molecular mass increases.
- The chemical properties also show a gradient similarity.
Example: Methane and ethane react with chlorine to form methyl chloride and ethyl chloride, respectively.
CH4 + Cl2 → CH3Cl
C2H6 + Cl2 → C2H5Cl - All members of a homologous series can be prepared by the same general method of preparation.
Example: Alcohols can be prepared from alkyl halides.
`CH_3Br+KOH " Boil"/""CH_3OH+KBr`
`C_2H_5Br+KOH " Boil"/""C_2H_5OH+KBr`
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संबंधित प्रश्न
Write the next homologue of the following: C4H6
Write the name and formula of the 2nd member of homologous series having general formula CnH2n.
Write the name and formula of the 2nd member of homologous series having general formula CnH2n + 2.
The following vegetables are kept in a basket :
Potato, Tomato, Radish, Brinjal, Carrot, Bottle-gourd
Which two of these vegetables correctly represent the homologous structures?
(A) Carrot and Tomato
(B) Potato and Brinjal
(C) Radish and Carrot
(D) Radish and Bottle-gourd
Give the structural formula for 1, 2-dichloroethane
What is the difference between two consecutive homologues:
(1) in terms of molecular mass?
(2) in terms of number and kind of atoms per molecule?
The molecular formula of an organic compound is C18H36. Name its homologous series.
The molecular formula of a homologue of butane is:
(a) C4H8
(b) C3H6
(c) C4H6
(d) C3H8
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
A colourless organic liquid X of molecular formula C2H4O2 turns blue litmus to red. Another colourless organic liquid Y of molecular formula C3H6O has no action on any litmus but it is used as a nail polish remover. A yet another colourless organic liquid Z of molecular formula C2H6O has also no action on litmus but it is used in tincture of iodine.
(a) Name the liquid X. To which homologous series does it belong? Give the name of another member of this homologous series.
(b) Name the liquid Y. To which homologous series does it belong? Write the name of another member of this homologous series.
(c) Can you name an organic compound having the same molecular formula as liquid Y but which belongs to a different homologous series? What is this homologous series?
(d) Name the liquid Z. To which homologous series does it belong? Write the name of another member of this homologous series.
Give the names and the structural formula of the first three members of the homologous series of alkanes.
Write names of first four homologous series of alcohols.
While going in an increasing order there is a rise in the molecular mass of the consecutive members of the homologous series by _______.
Find the odd one out and give its explanation.
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 |
The first member of alkyne homologous series is
Name the following organic compound:
The first homologue whose general formula is CnH2n.
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 C3H6.
- 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.
Name the following:
Group of organic compounds where the successive members follow a regular structural pattern, successive compounds differ by a 'CH2' group.
