(a) Illustrate the following reactions giving a suitable example for each.
(i) Cross aldol condensation
(ii) Decarboxylation
(b) Give simple tests to distinguish between the following pairs of compound
(i) Pentan-2-one and pentan-3-one
(ii) Benzaldehyde and Acetophenone
(ii) Phenol and Benzoic acid

Explanation

(i) Pentan-2-one is methyl ketone, It gives iodoform test (yellow ppt.) Pentan-3-one does not respond to this test since it is not a methyl ketone.
(ii) Acetophenone `(C_(6)H_(5)COCH_(3))` being a methyl ketone responds to iodoform test (yellow ppt.).Benzaldehyde `(C_(6)H_(5)CHO)` does not given this test.