The negative charge on acetone’s conjugate base is stabilized by resonance.
Explanation:
The resonance structures with negative charge on Carbon and Oxygen is shown in the attached file. Please refer the attached file.
Since the negative charge on acetone's conjugate base is stabilized by resonance structure that is not possible in propane since there is no double bond or an atom with lone pair of electrons.
Thus, the answer is – The negative charge on acetone’s conjugate base is stabilized by resonance.
