JEE Advanced (Fill in the Blanks): Haloalkanes & Haloarenes

Fill in the Blanks

1. The halogen which is most reactive in the halogenation of alkanes under sunlight is ................. . (chlorine, bromine, iodine) (1981 - 1 Mark)
 Ans: chlorine

Solution : Chlorine; because rate of formation of ^•CH₃ (one of the propagating steps) is high when X^• is Cl.
CH₄ + X^• → ^•CH₃ + H - X

2

. The compound prepared by the action of magnesium on dry ethyl bromide in ether is known as ............. reagent. (1982 - 1 Mark)
 Ans:  Grignard

Solution : Grignard (RMgX)

3. The interaction of elemental sulphur with Grignard reagent gives .............. . (1991 - 1 Mark)
 Ans: Thioalcohol

Solution : Thioalcohol

4. Vinyl chloride on reaction with dimethyl copper gives ............... . (1997 - 1 Mark)
 Ans : polyvinyl chloride

Solution : polyvinyl chloride

True/False

1. m-Chlorobromobenzene is an isomer of m-bromochlorobenzene. (1985 - ½ Mark)
 Ans:  False

Solution : False : m-Chlorobromobenzene and m-bromochlorobenzene is one and the same compound.

2. The reaction of vinyl chloride with hydrogen iodide to give 1-chloro-1-iodoethane is an example of anti-Markovnikov's rule.    (1989 - 2 Marks)

Ans:  False

Solution : 

This is an example of Markownikoff's rule as I^- is added at the C with less number. of H-atoms.
NOTE : anti-Markonikov's rule is applicable only to HBr, but not to HI and HCl.