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Arrange the following ia decreasing order of their boiling points.
(A) n-Butane
(B) 2-Methylbutane
(C) n-Pentane
(D) 2,2-Dimethylpropane
(a) A > B > C > D
(b) B > C > D > A
(c) D>C>B>A
(d) C >B>D > A

-OCH3 group is an activating group with +I effect whereas -Cl and -NO2 are groups due to their -I and -M effect. CH3 is electron donating group while Cl and NO2 are electron withdrawing group. The presence of electron withdrawing group decreases the electron density in the benzene ring making it more favourable for nucleophile attack whereas the presence of electron donating group favours electrophile attack.

Hence the correct order is methoxy benzene>chlorobenzene>nitrobenzene.

The reaction of mixture of alkyl halide in presence sodium metal is known as Wurtz reaction. Since here the given alkyl iodides are unsymmetrical with each other, so there are probability of formation of total three types of higher alkene. 1) when they condence with each other formed 2,4-dimethyl pentane, 2) when they react own self produce a) 2,5-dimethyl hexane (for former one) and b) 2,3-dimethyl butane (for later one).