Di-tertbutyl, ketone<methyl, tert-butyl ketone<acetone<acetaldehyde, Di tert butyl is sterically crowded by 2 tert butyl group around Keto group, Methyl tert butyl is also crowded but it is less compared di tert butyl. And acetone has only one Methyl group and acetaldehyde have no group around aldehydic carbon. We know that steric hinderance around active centre reduces reactivity.