NEETChemistryAmines
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Guanidine is a much stronger organic base than urea. Reason (R): The conjugate acid of urea is stabilized by three equivalent resonance structures. In the light of the above statements, choose the most appropriate answer from the options given below.
Options
- ABoth Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
- BBoth Assertion (A) and Reason (R) are true but Reason (R) is not the correct explanation of Assertion (A).
- CAssertion (A) is true but Reason (R) is false.
- DAssertion (A) is false but Reason (R) is true.
Correct answer
C. Assertion (A) is true but Reason (R) is false.
Step-by-step solution
Guanidine is a very strong organic base because its conjugate acid (guanidinium ion) is highly stable due to three equivalent resonance structures. Urea is a very weak base because its nitrogen lone pairs are involved in resonance with the electronegative carbonyl oxygen, making them unavailable for protonation. Therefore, Assertion (A) is true. Reason (R) is false because it is the conjugate acid of guanidine, not urea, that is stabilized by three equivalent resonance structures. Answer: Assertion (A) is true but