JEE MainChemistryAlcohols Phenols and EthersMCQ+4 / −1
Given below are two statements : Statement (I) : p-nitrophenol is more acidic than m-nitrophenol and o-nitrophenol. Statement (II) : Ethanol will give immediate turbidity with Lucas reagent. In the light of the above statements, choose the correct answer from the options given below :
- AStatement I is true but Statement II is false
- BBoth Statement I and Statement II are true
- CBoth Statement I and Statement II are false
- DStatement I is false but Statement II is true
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Correct answer: A
- Evaluate Statement (I): Acidity of nitrophenols
The acidity of nitrophenols depends on the stability of the corresponding phenoxide ion.
- The group is a strong electron-withdrawing group.
- At the para and ortho positions, it shows both:
- effect (inductive withdrawal)
- effect / resonance withdrawal
- At the meta position, only the effect operates effectively; resonance interaction with the phenoxide ion is not possible.
So, compared to -nitrophenol, both - and -nitrophenol should be more acidic due to extra resonance stabilization.
However, between -nitrophenol and -nitrophenol:
- -nitrophenol shows intramolecular hydrogen bonding, which stabilizes the neutral molecule and reduces its tendency to lose in water.
- Hence, -nitrophenol is more acidic than -nitrophenol.
Therefore, the acidity order is:
Thus, the statement is true.
- Evaluate Statement (II): Ethanol with Lucas reagent
Lucas reagent is a mixture of:
It is used to distinguish alcohols:
- Tertiary alcohols: immediate turbidity
- Secondary alcohols: turbidity in a few minutes
- Primary alcohols: no immediate turbidity at room temperature
Ethanol is a primary alcohol. So ethanol does not give immediate turbidity with Lucas reagent.
Hence, Statement (II) is false.
- Conclusion
- Statement (I): True
- Statement (II): False
Therefore, the correct option is:
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