Among the given pairs, in which pair first compound reacts faster than second compound in`S_(N^1)` ` reaction ?

Options

A. `CH_(3)-CH_(2)-CH_(2)-CH_(2)-Br" or "CH_(3)-CH_(2)underset(Br)underset(|)"-CH"-CH_(3)`
B. `CH_(3)-overset(CH_3)overset(|)underset(CH_3)underset(|)C-CH_(2)-CH_(2)Br" or "CH_(3)-underset(Br)underset(|) CH-overset(CH_3)overset(|)"CH"-CH_(3)`
C.
D. `CH_(3)-overset(CH_(3))overset(|)underset(Br)underset(|)C-CH_(3)" or "CH_(3)-overset(CH_(3))overset(|)underset(I)underset(|)"C"-CH_(3)`

Answer

B

Explanation

`CH_(3)- overset(CH_3)overset(|)underset(Br)underset(|)C-CH_2-CH_3` rate of reaction is faster than `CH_3 - underset(Br)underset(|)CH- overset(CH_3)overset(|)CH-CH_3`
because in former compound stable `C^(oplus)` is formed.