KEAM 2014 Physics and Chemistry Paper

since, the compound reacts with Tollen's reagent so it must contain a - CHO (aldehyde) group. Further, it does not give aldol condensation, it means that in it, α -hydrogen atom(s) is (are) absent. The structure of the given compound is as

CH3 α C H2 O || C − α C H2CH3

3−pentanone

(No-CHO group but α−H atoms present )

CH3‌

α CH3 |‌‌‌ CH

|‌‌‌ CH3

−CHO
2,2 -dimethyl propanaol
(have - CHO group and no α−H atom is present)
CH3−CH=

‌‌‌OH |

C

−CH2CH3
3 -hydroxy-2-pentene
(No - CHO group)
CH3

CH3 |‌‌‌

CH

α

C

H2CHO
3 -methyl butanal
(have - CHO group and α−H atom )
CH3

CH3 |‌‌‌

CH

−

O ||

C

−CH3
(No - CHO group and one α−H atom )
Thus, A is 2,2 -dimethylpropanal (as it contains a - CHO group but no α - H atom).