Keto-enol tautomers and ortho effect in drawn compounds

13 questions on Keto-enol tautomers and ortho effect in drawn compounds from the General Organic Chemistry II: Acids and Bases chapter: 3 NEET level, 3 JEE Main, 7 JEE Advanced. Each one opens with its answer and solution.

• Four carbonyl compounds are shown beside the options (the drawn compound is acetone, for reference). Which structure cannot form an enol? NEET level, drawn structure
• Which of the structures shown is the enol tautomer of the ketone drawn? NEET level, drawn structure
• The compound shown is an ortho-substituted benzoic acid. It is a stronger acid than benzoic acid mainly because NEET level, drawn structure
• The ketone shown can form enols by loss of an alpha hydrogen. Count all distinct enol forms (OH on a carbon that was the carbonyl carbon), counting E and Z isom... JEE Main level, drawn structure
• The structures shown are four tautomers/isomers of the diketone drawn. Which one is the most stable? JEE Advanced level, drawn structure
• The compound drawn is acetone. Four other carbonyl compounds are shown beside the options. Select ALL the structures that have a higher enol content than aceton... JEE Main level, drawn structure
• Four anilines are shown beside the options (the drawn compound is toluene). Which structure is the weakest base? JEE Advanced level, drawn structure
• Four nitro- and methyl-substituted benzoic acids are shown beside the options (the drawn compound is benzoic acid, pKa 4.20). Which structure is the strongest a... JEE Advanced level, drawn structure
• The compound shown is the hydroxy form of a heteroaromatic lactam. In water it exists mainly as which of the tautomers shown? JEE Advanced level, drawn structure
• Four carbonyl compounds are shown beside the options (the drawn compound is acetone, for reference). Select ALL the structures that cannot give an enol under or... JEE Advanced level, drawn structure
• The ketone shown has two different alpha carbons. Counting only enols with the OH on the former carbonyl carbon and counting E and Z isomers separately, how man... JEE Main level, drawn structure
• The compound shown is a 1,3-diketone. Select ALL the correct statements. JEE Advanced level, drawn structure
• Four nitro- or chloro-substituted anilines are shown beside the options (the drawn compound is aniline, pKaH 4.6). Which structure is the weakest base? JEE Advanced level, drawn structure