Which of the following reagents gives the same reduction product...

Propionaldehyde is $CH_3CH_2CHO$ and acetone is $CH_3COCH_3$.

Reduction with $LiAlH_4$, $Ni / H_2$, or $Na-Hg / HCl$ converts propionaldehyde to 1-propanol (CH_3CH_2CH_2OH$) and acetone to 2-propanol (CH_3CH(OH)CH_3$), which are different products.

Reduction with $Zn-Hg / Conc. HCl$ (Clemmensen reduction) reduces the carbonyl group to a methylene group. Thus, both propionaldehyde and acetone are reduced to propane (CH_3CH_2CH_3$), giving the same product.<br><br>Answer: \text{Zn-Hg}\ /\ \text{Conc HCl}$