(CH3)2 CH-CHO has one α - H atom whereas α -H atom is absent in (CH3)3 -CHO.
Detailed Answer:
Aldol condensation occurs due to presence of α -hydrogen. As (CH3)3CH-CHO has one α -H atom whereas (CH3)3C-CHO does not have α - H atom. Thus, (CH3)3CH-CHO undergoes aldol condensation whereas (CH3)3C-CHO does not.