Answer:
Option b is correct.
Explanation:
When [tex]Fe(NO_3)_3[/tex] is dissolved in water, [tex]Fe(OH)_2[/tex] and [tex]HNO_3[/tex] are formed.
[tex]Fe(NO_3)_3\; + 3H_2O \leftrightharpoons Fe(OH)_2\; + HNO_3[/tex]
As [tex]Fe(OH)_2[/tex] is an weak base and [tex]HNO_3[/tex] is a strong acid, the resulting solution will be acidic in nature.
if K_b value is known, then pH of the solution can also be determined which will support prediction.
However, acidic and basic nature of the solution can be predicted without K_b value also.
So, among the given option, (b) is correct.