Arrange the following compounds in increasing order of their acid strength: Propan-1-ol, 2,4,6-trinitrophenol, 3-nitrophenol, 3,5-dinitrophenol, phenol, 4-methylphenol.

Explanation

The increasing order of acidic strength is :
Propan-1-ol `lt` 4-methylphenol `lt` 3-nitrophenol `lt` phenol `lt` 3, 5-dinitrophenol `lt` 2, 4, 6-trinitrophenol.
Explanation : The increasing order of acidic strength is based upon the following facts about the acidic strengths of alcohols and phenols.
`**` Phenol is a stronger acid than alcohol.
`**` Methyl `(-CH_(3))` group being electron releasing in nature, decreases the acidic strength of phenol.
`**` Nitro `(-NO_(2))` group being electron withdrawing in nature, increases the acidic strength of phenol.