Give the decreasing order of reactivity for the following coupling compounds with ` PhN_2 Cl`.
a. I. Aniline II. Phenol III. Toluene IV. Chlorobenzene V. Nitrobenzee
b. I. toluene II. Ethyl benzene III. Cymene IV. T-Butyl benzene V. Anisole .

Explanation

The more ` EDG` in coupling compound, the faster the couling is .
a. `(I) gt (II) gt (III) gt (IV) gt (V)`
`ED` power of
`-ddotNH_(2) gt -ddotunderset(..)OH gt Me- gt -CI gt -NO_(2)`
b. `(V) gt (I) gt gt (II) gt (III) gt (IV)`
`ED` power of: `-ddotunderset(..)OM gt -Me` (Three `H.C.` structures and `+I)`
`gt -CH_(2)CH_(3)` (two `H.C.` structures and `+I)`
`gt Me_(2)CH_(3)` (two `H.C.` structures and `+I)`
`gt Me_(3)C-(t-butyl)` (No H.C. only `+I)`