The decreasing order of nucleophilicity among the following nucleophiles:

(a) ${\mathrm{CH}}_3{\mathrm{COO}}^{-}$

($\mathrm{b}$) ${\mathrm{CH}}_3{\mathrm{O}}^{-}$

($\mathrm{c}$) ${\mathrm{CN}}^{-}$

(d) 

Consider the following bromides

(A) 

(B) 

(C) 

The correct, order of ${\mathrm{S}}_{\mathrm{N}}1$ reactivity is

The main product of the following reaction is:

${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CH}}_2\mathrm{CH}\left(\mathrm{OH}\right)\mathrm{CH}{\left({\mathrm{CH}}_3\right)}_2\stackrel{ \mathrm{conc}. {\mathrm{H}}_2{\mathrm{SO}}_4}{⟶}$