Mark the correct order of decreasing acid strength of the following compounds

Options

A. `(V) gt (IV) gt (II) gt (I) gt (III) `
B. `(II) gt (IV) gt (I) gt (III) gt (V)`
C. `(IV) gt (V) gt (III) gt (II) gt (I)`
D. `(V) gt (IV) gt (III) gt (II) gt (I)`

Answer

B

Explanation

Both m-nitrophenol and o-nitrophenol are stronger acids than phenol because electron withdrawing groups such as `-NO_(2)` group increase the acidity of phenols. However, due to the combined - I and - R effect of `-NO_(2)` group at para position, p-nitrophenol is a much stronger acid than m-position.
`-OCH_(3)` group exerts - I and + R effect at p-position and thus p-methoxyphenol is a weaker acid than phenol. However, m-Methyoxyphenol is a stronger acid than phenol because `-OCH_(3)` group can not exert its + R effect at m-position and only - I effect operates at m-position. Thus, the acid strength `(II) gt (IV) gt (I) gt (V)`.