An unsaturated hydrocarbon $$[\mathrm{A}]$$ reacts with $$\mathrm{HBr}$$ in presence of Benzoyl peroxide to yield [B] Compound [A] when reacted with cold, dilute alkaline $$\mathrm{KMnO}_4$$ gave compound [C], 2-Methylbutane-2, 3-diol But when [A] is reacted with hot $$\mathrm{KMnO}_4$$, it yielded $$\mathrm{CH}_3 \mathrm{COOH}$$ and a compound [D] Identify compounds [A], [B] and [D]

An aromatic hydrocarbon $$[\mathrm{A}]\left(\mathrm{Molecular}\right.$$ formula $$\left.\mathrm{C}_9 \mathrm{H}_{12}\right)$$, undergoes air oxidation followed by reaction with dil. $$\mathrm{HCl}$$ to give [B] as one of the products

Compound [B] forms a white precipitate on treatment with $$\mathrm{Br}_2(\mathrm{aq})$$

Sodium salt of [B] reacts with $$\mathrm{CO}_2$$ at $$400 \mathrm{~K}$$ under high pressure followed by acid hydrolysis to give [C]

Compound [C] reacts with acetic anhydride / conc. $$\mathrm{H}_2 \mathrm{SO}_4$$ to form [D] Identify compound $$[\mathrm{D}]$$

Ammoniacal silver nitrate forms a white precipitate easily with

The conversion of Propyne to Benzene can be brought out in 4 steps.

Choose the reagents to be used, in the proper sequential order, to bring out the conversion.

Reagents provided: alc. $$\mathrm{KOH}, \mathrm{H}_2 / \mathrm{Pd}, \mathrm{Na} /$$ dry ether, $$\mathrm{HBr}, \mathrm{HBr} /\left(\mathrm{C}_6 \mathrm{H}_5 \mathrm{CO}\right)_2 \mathrm{O}_2$$, Soda-lime, $$\mathrm{Cr}_2 \mathrm{O}_3$$ (high T and P), Conc. $$\mathrm{H}_2 \mathrm{SO}_4$$