Grignard reagents (RMgX) are highly reactive towards moisture. If water is present, it reacts with the Grignard reagent, forming an alkane instead of undergoing the desired reaction. This is why anhydrous conditions are necessary during preparation and storage.
Observe the following reaction and same reaction is carried out with the following compound: 
X and Y can be differentiated by:


Would you expect benzaldehyde to be more reactive or less reactive in nucleophilic addition reactions than propanal? Justify your answer.