Which of the following order is correct?

Answer

Acid strength order : `II gt IV gt III gt I`

Explanation

Step-1: In nitrophenols -I effect of `NO_(2)` will help to increase acidic strength hence phenol is least acidic amongst all nitrophenols
Steps-1: Only-I effect is applicable in meta nitrophenol is will is number three. Now -o,-p have both -I and -m effect of `NO_(2)` group over OH and in this particlular case para isomer is more acidic than ortho since