Of all the three common mineral acids,only sulphuric acid is found to be suitable for making the solution acidic in redox titrations involving $KMnO_4$ because:

Given below are two statements
Statement $I$: Aqueous solution of $K_2Cr_2O_7$ is preferred as a primary standard in volumetric analysis over $Na_2Cr_2O_7$ aqueous solution.
Statement $II$: $K_2Cr_2O_7$ has a higher solubility in water than $Na_2Cr_2O_7$.
In the light of the above statements,choose the correct answer from the options given below:

Given below are two statements: One is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: Permanganate titrations are not performed in the presence of hydrochloric acid.
Reason $R$: Chlorine is formed as a consequence of the oxidation of hydrochloric acid.
In the light of the above statements,choose the correct answer from the options given below.

In the iodometric estimation in the laboratory,which process is involved?

The number of equivalents of $Na_2S_2O_3$ required for the volumetric estimation of one equivalent of $Cu^{2+}$ is

$KMnO_4$ is titrated with ferrous ammonium sulphate hexahydrate in the presence of dilute $H_2SO_4$. The number of water molecules produced for $2$ molecules of $KMnO_4$ is $..........$.