Question

Arrange the following compounds in increasing order of their property as indicated: Benzoic acid, 4-Nitrobenzoic acid, 3,4-Dinitrobenzoic acid, 4-Methoxybenzoic acid (acid strength)

Answer 1

Arrange the following compounds in increasing order of their properties as indicated: ... (iii) (iv) (v) (vi) (vii) Phenol and benzoic acid can ...

Answer 2

The donation of the electron will decrease the strength of the respective acids whereas it will gives opposite reaction on the withdrawing the electron.

The methoxy group will fall in the category of electron-donating group that will make 4-methoxybenzonic acid weaker as compared to benzoic acid.

Similarly, the nitro group will be in withdrawing group making it slightly stronger.

Hence.  

4-methoxybenzoic acid < Benzoic acid < 4-Nitrobenzoic acid

< 3,4-Dinitrobenzoic acid