In the reaction sequence, C6H5CHONH2OH/H+−−−−−−−−→△(X)P2O5−−−→△(Y)H2O/H+−−−−−→(Z) X, Y and Z respectively are:
Predict the order of reactivity of the following compounds in SN1 and SN2 reactions
C6H5CH2Br , C6H5CH(C6H5)Br , C6H5CH(CH3)Br , C6H5C(CH3)(C6H5)