Redox Reactions Questions

The oxidation state of chromium in the final product formed by the reaction between $\text{KI}$ and acidified potassium dichromate solution is:

Which of the following chemical reactions depicts the oxidizing behaviour of ${\text{H}}_2{\text{SO}}_4$?

Excess $\text{KI}$ reacts with ${\text{CuSO}}_4$ solution and then ${\text{Na}}_2{\text{S}}_2{\text{O}}_3$ solution is added to it. Which of the following statements is incorrect for this reaction?

Amount of oxalic acid present in a solution can be determined by its titration with ${\text{KMnO}}_4$ solution in the presence of ${\text{H}}_2{\text{SO}}_4$. The titration gives unsatisfactory results when carried out in the presence of $\text{HCl}$ because $\text{HCl}$:

The standard reduction potentials for ${\text{Zn}}^{2+}/\text{Zn}$, ${\text{Ni}}^{2+}/\text{Ni}$, and ${\text{Fe}}^{2+}/\text{Fe}$ are $-0.76$, $-0.23$ and $-0.44\text{V}$ respectively. The reaction $\text{X}+{\text{Y}}^{2+}\to {\text{X}}^{2+}+\text{Y}$ will be spontaneous when: