i. Ethanol to but-1-yne

ii. Ethane to bromoethene

iii. Propene to 1-nitropropane

iv. Toluene to benzyl alcohol

v. Propene to propyne

vi. Ethanol to ethyl fluoride

vii. Bromomethane to propanone
\(CH_3−Br\overset{KCN}{\longrightarrow}CH_3−CN\overset{CH_3−Mg−Br}{\longrightarrow}CH_3−CCH_3=NMgBr\overset{hydrolysis}{\longrightarrow}CH_3−CO−CH_3\)
viii. But-1-ene to but-2-ene

ix. 1-Chlorobutane to n-octane

x. Benzene to biphenyl

A compound (A) with molecular formula $C_4H_9I$ which is a primary alkyl halide, reacts with alcoholic KOH to give compound (B). Compound (B) reacts with HI to give (C) which is an isomer of (A). When (A) reacts with Na metal in the presence of dry ether, it gives a compound (D), C8H18, which is different from the compound formed when n-butyl iodide reacts with sodium. Write the structures of A, (B), (C) and (D) when (A) reacts with alcoholic KOH.
