Solution
We know that +I groups (−CH
3
) in Phenols decrease its acidity while -I groups (−NO
2
) increase it. Therefore, the correct order of increasing acidity is:
Propan-1-ol < 4-methylphenol < Phenol < 3-nitrophenol < 3,5-dinitrophenol < 2,3,6-trinitrophenol