(i) Organometallic compounds are organic compounds in which there is a direct carbonmetal bond.
(ii) Example: CH₃MgI, methyl magnesium iodide.
(iii) The carbon-magnesium bond in Grignard reagent is covalent but highly polar. The carbon atom is more electronegative than magnesium. Hence, the carbon atom has partial negative charge and magnesium atom has a partial positive charge
\(\overset { \delta - }{ R } ...........\overset { \delta + }{ MgX } \)

(i) Carbon tetrachloride in used as a dry cleaning agent.
(ii) It is used as a solvent for oils, fats and waxes.
(iii) As the vapours of CCl₄ is non-combustible, it is used under the name pyrene for extinguishing the fire caused by oil (or) petrol.

(i) Chloroform is used as a solvent in pharmaceutical industry.
(ii) It is used for producing pesticides and drugs.
(iii) It is used as an anaesthetic.

(i) 
According to Saytzeff's rule, when 2-bromobutane reacts with alcoholic KOH, yields a mixture of olefins in different amounts.
(ii) In a dehydrohalogenation reaction, the preferred product is that alkene which has more number of alkyl groups attached to the doubly bonded carbon alkene.

(i) 2-bromobutane is optically active and it undergoes S_N¹ reaction with aqueous KOH.
(ii) The product obtained will be an optically inactive racemic mixture.
(iii) As nucleophilic reagent OH^- ion can attack the carbocation from both sides to form equal proportions of dextro and levo rotatory optically active isoiners, it results in the formation of optically inactive racemic mixture.