Explanation

(c)
$CH_{2} = CHCH = CH_{2} + HBr \rightarrow$
$CH_{3}CHCH = CH_{2} + CH_{3}CH = CHCH_{2}Br$
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$Br$
1,2-addition product 1,4-addition product
Addition is through the formation of allylic carbocation.
[image:13_image304.emf]$CH_{2} = CHCHCH_{3} \leftrightarrow CH_{3}CH = CHCH_{2}$
Under mild conditions (temperature$\approx - 80℃$) kinetic product is the 1, 2-addition product and under vigorous conditions (temp. $\approx 40℃$) thermodynamic product is the 1,4-addition product.
Thus, 1-bromo-2-butene is the major product under given condition.