(A) , (B) and (C) are three non-cyclic functional isomers of a carbonyl compound with molecular formula `C_(4)H_(8)O` . Isomers (A) and (C) give positive Tollen's test whereas isomer (B) does not give Tollen's test but gives positive Iodoform test . Isomers (A) and (B) on reduction with Zn(Hg)/conc. HCl gives the same product (D).
(a) Write the structure of (A) , (B) and (C) and (D) .
(b) Out of (A) , (B) and (C) isomers , which one is least reactive towards addition of HCN ?

Explanation

According to available information, (A) , (B) and (C) are all non-cylic carbonyl compounds. Since (A) and (C) give positive Tollen's test, they must have an aldehydic group. As the isomer (B) does not respond to Tollen's test but gives positive iodoform test, it must be a methyl ketone. The structural formulae of the three isomers are

(b) Out of the isomers, (B) should be least reactive towards addition of HCN.