Give simple chemical test to distinguish between the following pairs of compounds.
i. Propanal and Propanone
ii. Acetophenone and Benzophenone
iii. Phenol and Benzioc acid
iv. Benzoic acid and Ethyl benzoate
v. Pentan-2-one and Pentan-3-one
vi. Benzaldehyde and Acetophenone
vii. Ethanal and Propanal

Explanation

(i) Propanal and propanone. Propanal will give silver mirror upon heating with Tollen's reagent but propanone will not respond.
(ii) Phenol and benzoic acid. Benzoic acid will give brisk effervescence with sodium hydrogen carbonate `(NaHCO_(3))` but phenol will not respond
(iii) Acetophenone and benzophenone. Acetophenone is a methylketone. It will give a yellow precipitate upon heating with `I_(2)" and "NaOH`. Benzophenone will not respond.
(iv) Benzoic acid and ethyl benzoate. Benzoic acid will give brisk effervescence with sodium hydrogen carbonate `(NaHCO_(3))` but ethyl benzoate (ester) will not respond.
(v) Pentan-2-one and pentan-3-one. Pentan-3-one is a methyl ketone and will give a yellow precipitate upon heating with `I_(2)" and "NaOH`. Pentan-3-one will not respond.
(vi) Benzaldehyde and acetophenone. The distinction can also be made by iodoform test. Acetophenone will give yellow precipitate while benzaldehyde will not react.
(vi) Ethanal and propanal. Ethanal will respond to iodoform test and give yellow precipitate. Propanal will not react. For more details and chemical equations, consult section 13.8.