The decreasing order of reactivity towards electrophilic substitution of the following compounds is

Step-by-step solution

Due to +I -effect of - CH ₃ group (4) has higher electron density, than benzene (1). Due to strong -I -effect of - Cl group and strong -I and -M -effect of - NO ₂ group, both (2) and (3) have lower electron density, than benzene (l). As - I-effect of -Cl group is weaker, than that of - NO ₂ (3) has much lower electron density than (2). Hence, nitrobenzene will have high reactivity towards electrophilic substitution due to lower electron density on benzene ring. Thus, the overall reactivity order towards electrophil