Question

why hcl and hno3 cannot be used instead of h2so4 in the titration of mohr salt?

Answer 1

Thanks for asking the question.
HCl and HNO3 are not used in the titration of Mohr's salt in place of sulfuric acid because:
HCl is a mild reducing agent and it reacts with some of the indicator that is KMnO4 solution so the final value of the indicator used come to be more than the actual value disturbing the experiment.
HNO3 is also a powerful oxidizing agent along with KMnO4 so it also plays its role in oxidation which causes a decline in the value of KMNo4 used.
As dilute sulfuric acid is ideal for redox titration because it is neither an oxidizing agent and nor a reducing agent.
Hope it helps

Answer 2

HCL being a strong electrolyte dissociates in water to give H+ and Cl- ions.

KMnO4 being a strong oxidising agent oxidises Chloride ion(Cl-) to Cl2. Hence ssome amount of KMnO4 is used up in oxidising Cl- to Cl2. Side by side KMnO4 is oxidising oxalate ion to CO2. Hence more amount of KMnO4 is used up which results in error in reading.