Which of the following redox reactions is thermodynamically non-spontaneous under standard conditions at 298 K?

Given the standard reduction potentials:

E°(Cu²⁺/Cu) = +0.34 V
E°(Zn²⁺/Zn) = −0.76 V
E°(Fe²⁺/Fe) = −0.44 V
E°(Ag⁺/Ag) = +0.80 V

1. CuSO₄(aq) + 2Ag(s) → Cu(s) + Ag₂SO₄(aq)

2. CuSO₄(aq) + Zn(s) → ZnSO₄(aq) + Cu(s)

3. CuSO₄(aq) + Fe(s) → FeSO₄(aq) + Cu(s)

4. FeSO₄(aq) + Zn(s) → ZnSO₄(aq) + Fe(s)

The oxidation states of the central atom in the given species are, respectively:

${\mathrm{H}}_4{\mathrm{P}}_2{\mathrm{O}}_7$ $$ $\mathrm{and}$ ${\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_7$

KI₃, H₂S₄O₆

The oxidation numbers of iodine and sulphur in the above compounds are, respectively:

The oxidation state of P in ${\mathrm{HPO}}_3^{2-}$ is-

Which of the following reactions does not involve disproportionation process?

1. ${\mathrm{Cl}}_2+{\mathrm{OH}}^{-}\to {\mathrm{Cl}}^{-}+{\mathrm{ClO}}_3^{-}+{\mathrm{H}}_2\mathrm{O}$

2. $2{\mathrm{H}}_2{\mathrm{O}}_2\to {\mathrm{H}}_2\mathrm{O}+{\mathrm{O}}_2$

3. $2{\mathrm{Cu}}^{+}\to {\mathrm{Cu}}^{2+}+\mathrm{Cu}$

4. ${\left({\mathrm{NH}}_4\right)}_{2}C{r}_2{O}_7\to {\mathrm{N}}_2+{\mathrm{Cr}}_2{\mathrm{O}}_3+4{\mathrm{H}}_2\mathrm{O}$

The oxidation number of sulphur and nitrogen in H₂SO₅ and NO₃^- are respectively-