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प्रश्न
Write a short note.
Homologous series
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उत्तर
- The series of carbon compounds formed by joining the same functional group in the place of a particular hydrogen atom on the carbon chains having sequentially increasing length is called homologous series.
- There are different homologous series in accordance with the functional group. For example, homologous series of alcohols, homologous series of carboxylic acids, homologous series of aldehydes, etc.
- All the members of the homologous series are homologues of each other and they can be represented by the same general molecular formula.
- Physical properties generally show a gradual change with the increase in molecular mass in the series whereas chemical properties of the members of the series show similarity because of the presence of the same functional group in them.
APPEARS IN
संबंधित प्रश्न
What is a homologous series?
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.
Write the molecular formula of first two members of homologous series having functional group – OH
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
Write the molecular formula of the 2nd and 3rd member of the homologous series where the first member is ethyne.
Fill in the following blank with suitable word:
Carbon compounds have usually ... melting points and boiling points because they are ...... in nature.
The molecular formula of the third member of the homologous series of ketones is:
(a) C4H8O
(b) C3H6O
(c) C5H10O
(d) C6H12O
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 structure of the second member of the alcohol group.
.
Write names of first four homologous series of alcohols.
Give the names of the first four members of the homologous series of
alkynes.
Haloalkanes react with alkalies to produce alcohol. Give the equation for the preparation of the second member of the homologous series of alcohol. State under what condition the reaction occurs.
The general formula of Alkane is _________________
Assertion (A): In a homologous series of alcohols, the formula for the second member is C2H5OH and the third member is C3H7OH.
Reason (R): The difference between the molecular masses of the two consecutive members of a homologous series is 144.
The unsaturated hydrocarbons containing a carbon-carbon double bond are called _______.
The phenomenon in which compounds having different structural formulae have the same molecular formula is called _______.
Complete the following chart by using examples given in brackets.
(isobutylene, cyclohexane, propane, cyclohexene, cyclopentane, benzene, propyne, isobutane, propene)
| Straight chain hydrocarbons | Branched chain hydrocarbons | Cyclic hydrocarbons |
Study and complete the following table:
| Homologous series | Alkane | Alkyne |
| General formula | CnH2n+2 | 1. ______ |
| IUPAC name | 2. ______ | Ethyne |
| Common name | Marsh gas | 3. ______ |
