Directions: In the following questions, a statement of assertion (A) ...
Assertion is correct but reason is false. Any two successive members in a homologous series differ in their molecular formula by — CH2— unit.
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Directions: In the following questions, a statement of assertion (A) ...
Assertion: C3H8 and C4H10 are the successive members of a homologous series of methane.
Reason: Any two successive members in a homologous series differ in their molecular formula by a -CH3 unit.
The correct answer is option 'C', which means Assertion (A) is true but Reason (R) is false.
Explanation:
A homologous series is a series of organic compounds that have the same functional group and show a gradual increase in molecular size and a regular increment in their chemical properties.
In the given assertion, C3H8 and C4H10 are mentioned as the successive members of a homologous series of methane. This means that they are part of a series of compounds that have the same functional group as methane (CH4) but differ in molecular size.
The reason given states that any two successive members in a homologous series differ in their molecular formula by a -CH3 unit. However, this is not true. In a homologous series, the successive members differ in their molecular formula by a -CH2 unit, not a -CH3 unit.
To understand this, let's consider the example of a homologous series of alkanes, which includes methane (CH4), ethane (C2H6), propane (C3H8), butane (C4H10), and so on. In this series, each member differs from the previous one by a CH2 unit.
Methane (CH4)
Ethane (C2H6) - differs from methane by CH2 unit
Propane (C3H8) - differs from ethane by CH2 unit
Butane (C4H10) - differs from propane by CH2 unit
As we can see, each member in the series differs by a CH2 unit, not a -CH3 unit as mentioned in the reason.
Therefore, the assertion is true as C3H8 and C4H10 are indeed successive members of a homologous series of methane. However, the reason is false as it incorrectly states that the difference between successive members is a -CH3 unit, whereas it should be a -CH2 unit.
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