Give simple chemical tests to distinguish between the following pairs of compounds.
(i) Pentan-2-one and Pentan-3-one
(ii) Ethanal and Propanal

Benzaldehyde can be obtained from benzal chloride.  Write reactions obtaining benzalchloride and then benzaldehyde from it.

Compound 'A' was prepared by oxidation 'B' with alkaline KMnO₄.  Compound 'A' on reduction with lithium aluminium hydride gets converted back to compound 'B'.  When compound 'A' is heated with compound B in the presence of H ₂SO₄ it produces fruitly smell of compound C to which family the compounds 'A', 'B' and 'C' belong to?

Alkenes \(\diagdown \quad \quad \quad \ \ \diagup \\( \ C = C \ ) \\ \diagup \quad \quad \quad \ \ \diagdown\) and carbonyl compounds \(\diagdown \\( \ C = O \quad ) \\ \diagup\), both contain a \(\pi\) - bond but alkenes show electrophilic addition reactions whereas carbonyl compounds show nucleophilic addition reactions.  Explain.

When liquid 'A' is treated with a freshly prepared ammoniacal silver nitrate solution, it gives bright silver mirror.  The liquid forms a white crystalline the solid on treatment with sodium hydrogensulphite.  Liquid 'B' also forms a white crystalline solid with sodium hydrogensulphite but it does not give test with ammoniacal silver nature.  Which of the two liquids is aldehyde?  Write the chemical equations of these reactions also.