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# $CH_3Br +Nu^{-} \longrightarrow CH_3 -Nu +Br^{-}$ The decreasing order of the rate of the above reaction with nucleophiles $(NU)$ A to D is $[Nu^{-}=\quad (A)\; Pho^{-},\;(B)\;AcO^- ,\; (C)\; HO^{-},\; (D)\;CH_3O^{-}]$

$(a) D > C > A > B \\ (b)\; D > C > B > A \\ (c) A > B > C > D \\ (d)B > D > C > A$

If the nucleophilic atom or the centre is same, nucleophilic parallels basicity ie more basic the species stronger is the nucleophile
$CH_3 O^{-} > HO^{-} > PhO^{-} > AcO^{-}$
Here, the nucleophilic atom is O is the same in all these species .
This order can be easily explained on the general concept that a weaker acid has a stronger conjugate base.
So, $(A) D > C > A > B$ is the correct answer.
edited Mar 21, 2014