Explain the position directional properties of groups in mono-substituted benzene with suitable examples.

(N/A) When a second substitution is carried out in mono-substituted benzene,the position of the incoming group is directed by the group already attached to the benzene ring. This phenomenon is known as the directive influence of the first group.
The position of the second substitution depends on the nature of the first substituent already present on the benzene ring,not on the nature of the incoming group.
There are two types of directive influences observed in benzene:
$(a)$ Ortho-para directing groups: These groups increase the electron density at the ortho and para positions,making them more reactive towards electrophilic substitution. Examples include $-OH, -NH_{2}, -NHR, -NHCOCH_{3}, -OCH_{3}, -R (\text{e.g., } -CH_{3}, -C_{2}H_{5}), -Cl, -F, -I, -Br$.
$(b)$ Meta directing groups: These groups decrease the electron density at the ortho and para positions,making the meta position relatively more favorable for electrophilic substitution. Examples include $-NO_{2}, -CN, -CHO, -COOH, -COR, -SO_{3}H, -COOR, -\stackrel{+}{NH}_{3}$.
If a meta-directing group is already present on the benzene ring,the incoming electrophile $(E^{+})$ will attach at the meta position.