Question

Question-5. Which one of the following alcohols is most acidic? ОН ОН ОН IV А. В. с. І || III IV

Answer 1

The acid, whose conjugate anion formed after removal of H+ will be most stable, would be most acidic as it would have highest tendency to get deprotonated.

Among the given acids of option I, II, and III, only in I the conjugate anion formed after removal of H+ from OH part takes part in resonance but II and III donot have such resonance stabilization possibility. So among I, II and III the strongest acid is I.

Now among I and IV, there is no OH on IV, the acidic H in it is on C atoms on both sides of C=O. Its conjugate anion will be able to take part in resonance but since OH is more acidic than CH, other factors being same, so I is more acidic than IV.

Hence answer is A. I.

Comment in case of any doubt.