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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.
Write the molecular formula of first two members of homologous series having functional group -Cl.
Write the molecular formula of first two members of homologous series having functional group −Br.
Write the molecular formula of the third member of the homologous series of carbon compounds with general formula CnHO2n+1OH.
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
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.
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Define homologous series of organic compounds. List its two characteristics. Write the name and formula of the first member of the series of alkenes.
Write names of first four homologous series of alcohols.
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 |
What is a homologous series?
Complete the correlation:
Alkene : C = C :: Alkyne: _______.
The general molecular formula for the homologous series of alkynes is _______.
Cyclohexane : Cyclic hydrocarbon : : Isobutylene : _______
Find the odd one out and give its explanation.
As one ascends in any homologous series, physical properties change gradually.
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.
Consider the following molecular formulae of carbon compounds:
(i) CH3COOH (ii) CH3OH (iii) C2H6 (iv) C3H4 (v) C4H8
- Which one of these compounds belongs to homologous series of alcohols?
- Identify the compound having triple bond between carbon-carbon atoms.
- Write the molecular formula of the first member of the homologous series to which CH3COOH belongs.
- Write the general formula of the series to which the compound C4H8 belongs.
Name and draw the electron dot structure of first homologue of alkynes series.
