Q. Given below are two statements : Consider the following reaction R₂C=O + H₂O ⇌ R₂C(OH)₂ (equilibrium constant K). Statement (I) : In the case of formaldehyde (HCHO), K is about 2280, due to small substituents, hydration is faster. Statement (II) : In the case of trichloroacetaldehyde (CCl₃CHO), K is about 2000 due to −I effect of −Cl. In the light of the above statements, choose the correct answer from the options given below:
A) Both Statement I and Statement II are false
B) Statement I is true but Statement II is false
C) Statement I is false but Statement II is true
D) Both Statement I and Statement II are true
Explanation
[Solution by Dr. Abubacker] Formaldehyde has the smallest substituents (two H) and the carbonyl carbon is least hindered, so hydration is extensive (K ≈ 2280). In chloral, the strongly electron-withdrawing CCl₃ group (−I effect) makes the carbonyl carbon highly electrophilic and stabilises the hydrate (K ≈ 2000). Both statements are true. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.