Which reagent can distinguish between pentanoic acid and pentanamide ?

Which of the following reagent/solution can be used to distinguish between methanoic acid and ethanoic acid?

How can you distinguish between an alcohol and an acid?

Which of the following is the suitable reagent to distinguish between carboxylic acid and phenol

Which of the following reagents can distinguish between acetaldehyde and benzaldehyde ?

How is 'Tollens' reagent used to distinguish between formic acid and acetic acid?