IIT JEE Advanced 2010 Paper 2

The products obtained on nitration of P, Q and S are

Here strongly activating and ortho-, para directing –OH group determines the site for electrophilic substitution.

Here –OCH3 is a stronger activator than –CH3 and both are ortho-, para directing.

Here, the substitution takes place on the activated ring (with substituent PhCOO−) at the sterically unhindered para- position.