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Question
Write the molecular formula of first two members of homologous series having functional group – OH
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Solution
The general formula for the homologous series of functional group −OH is CnH2n+1OH.
The two consecutive members of this series are:
a. CH3OH(Methanol)
b. CH3CH2OH (Ethanol)
where n is 1 and 2 respectively
The molecular formula for both of them are CH4O and C2H6O.
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RELATED QUESTIONS
State any four characteristics of a homologous series
Write the name and formula of the 2nd member of homologous series having general formula CnH2n.
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
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Write the molecular formula of the 2nd and 3rd member of the homologous series where the first member is ethyne.
What is a homologous series? Explain with an example.
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.
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(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.
What is the difference in the molecular formula of any two adjacent homologues in terms of molecular mass?
Study the different conclusions drawn by students of a class on the basis of observations of preserved/available specimens of plants and animals.
I. Potato and sweet potato are analogous organs in plants.
II. Wings of insects and wings of birds are homologous organs in animals.
III. Wings of insects and wings of bats are analogous organs in animals.
IV. Thorns of citrus and tendrils of cucurbita are analogous organs in plants.
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(D) III and IV
Copy and complete the following table, which relates to the three homologous series of hydrocarbons:
| General formula | CnH2n | CnH2n-2 | CnH2n+2 |
| IUPAC name of the homologus series | |||
| Characteristic bond type | Single bonds | ||
| IUPAC name of the first member of the series | |||
| Type of reaction with chlorine | Addition |
C3H8 belongs to the homologous series of ______.
