How do you convert: (i) Chlorobenzene to biphenyl (ii) Propene to 1-iodopropane (iii) 2-bromobutane to but-2-ene

(i) Chlorobenzene is converted to biphenyl by using Fittig reaction. Chlorobenzene reacts with sodium in presence of ether to form biphenyl
(ii) Propene to 1-iodopropane. The hydroboration-oxidation of propene gives 1-propanol. 1-propanol then reacts with HI (obtained from KI + H2SO4) to form 1-iodopropane
(iii) 2-bromobutane to but-2-ene. The dehydrohalogenation of 2-bromobutane in presence of alcoholic KOH gives but-2-ene as major product.