Answer
Least acidic --> Most acidic
$NH_3$ < $H_2O$ ~$CH_3OH$ < $CH_3COOH$ < $HF$ < $H_3O^+$ < $H_2SO_4$
Work Step by Step
Using the $pK_a$ values from table 1-5 and appendix 4, the answer can be determined. The lower the $pK_a$, the stronger the acid. The water and $CH_3OH$ are very close.
The $pK_a$ are given in the brackets.
Least acidic --> Most acidic
High $pK_a$ --> low $pK_a$
$NH_3$ (33) < $H_2O$ (15.7) ~$CH_3OH$ (15.5) < $CH_3COOH$ (4.74) < $HF$ (3.2) < $H_3O^+$ (-1.7) < $H_2SO_4$ (-5)
