a. In this reaction,reactant form even number carbon compound. When ethyl bromide is reacted with sodium metal in presence of dry ether, n-butane is obtained. This reaction is known as Wurtz's reaction. Ethyl bromide can be converted into n butane by wurtz reaction .

b. The chemical basis forMarkovnikov's Ruleis the formation of the most stable carbocation during the addition process. The addition of the hydrogen ion to one carbon atom in the alkene createsapositive charge on the other carbon, formingacarbocation intermediate.

c. Baeyer's reagentis an alkaline solution of cold potassium permanganate, which is a powerful oxidant making this a redox reaction. Reaction with double or triple bonds (-C=C- or -C≡C-) in an organic material causes the color to fade from purplish-pink to brown.

It is a syn addition reaction

d. Preparationofbenzenefromphenol.Benzenecan beprepared from phenolstoo through their reduction.

In this process vapors ofphenolare passed over heated zinc dust. Zinc dust reduces them to formbenzene.

e. Benzenehexachloride (BHC), any of several stereoisomers of 1,2,3,4,5,6-hexachlorocyclohexane formed by the light-induced addition of chlorine tobenzene.

One of these isomers is an insecticide called lindane, or Gammexane