Explain the formation of alcohols From Grignard reagents?

All the three types of monohydric alcohols (primary, secondary and tertiary alcohols) are obtained by the use of Grignard reagents and carbonyl compounds. The addition of RMgX on carbonyl compounds followed with hydrolysis yields alcohols.

The Grignard reagent : an organometallic compound

When a solution of an alkyl halide in dry ethyl ether, (C2H5)O, is allowed to stand over turnings of metallic magnesium a vigorous reaction takes place: the solution turns cloudy, begins to boil, and the magnesium metal gradually disappears. The resulting solution is known as a Grignard reagent, after Victor Grignard (of the University of Lyons) who received the Nobel prize in 1912 for its discovery. It is one of the most useful and versatile reagents known to the organic chemist.