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• Topic:

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Keto-enol tautomerism is observed in :

(a) C6H5$-\stackrel{\mathrm{O}}{\stackrel{||}{\mathrm{C}}}-$H

(b) C6H5$-\stackrel{\mathrm{O}}{\stackrel{||}{\mathrm{C}}}-$CH3

(c) C6H5$-\underset{\mathrm{O}}{\underset{||}{\mathrm{C}}}-$C6H5

(d) none of these