asalamualikum,pls elp me w this. The second one is also aldehyde so why the ans is d or one only.shudnt the second one also become a carboxailic acidn

[Abdullahbutt]

 

[Mr.Physics]

View attachment 65293

You are partially right. The second one is benzaldehyde which can be oxidised to benzoic acid, however, a part of question also says that the newly formed carboxylic acid should be readily soluble in cold water. Benzoic acid isn't READILY soluble in water because the only part which is polar in it is the carboxylic group. The rest of the molecule is non-polar. Same is the case with no. 3, therefore, only no.1 can be oxidised to form a carboxylic acid which is readily soluble in cold water.