The insecticide containing $99\%$ $\gamma-isomer$ of benzene hexachloride is known as

An alkyl bromide reacts with sodium ethoxide and ethanol to give only one alkene. Hydrogenation of this alkene yields $2-$methylbutane. What is the alkyl halide?

Which of the following statements is correct for optically active alkyl halides,upon reaction with nucleophiles?

	$S_{N}1$	$S_{N}2$
$(a)$	Retention of configuration	Inversion of configuration
$(b)$	Racemisation	Inversion of configuration
$(c)$	Inversion of configuration	Retention of configuration
$(d)$	Racemisation	Retention of configuration

Which of the following would not give $2-$phenylbutane as the major product in a Friedel-Crafts alkylation reaction?

The increasing rate of $S_N1$ reaction in the following compounds is:

Which of these does not form a Grignard reagent?