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:

1. \(\frac{1}{3}\) ; 4
2. 2.5 ; \(\frac{1}{3}\)
3. \(-\frac{1}{3}\) ; 2.5
4. 2.5 ; 3

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

${\mathrm{MnO}}_4^{2-}$ undergoes disproportionation reaction in acidic medium but ${\mathrm{MnO}}_4^{-}$ does not. It is:

The reaction that does not represent auto redox or disproportionation is: 

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

Assertion: In the presentation ${\mathrm{E}}_{{\mathrm{Fe}}^{3+}/{\mathrm{Fe}}^{2+}}^{⊝}$ and ${\mathrm{E}}_{{\mathrm{Cu}}^{2+}/\mathrm{Cu}}^{⊝}$, ${\mathrm{Fe}}^{3+}/{\mathrm{Fe}}^{2+}$ and ${\mathrm{Cu}}^{2+}/\mathrm{Cu}$ are redox couples.

Reason: A redox couple is the combination of the oxidised and reduced forms of a substance involved in an oxidation or reduction half cell.

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

Which of the following reactions does not represent a redox change?

1. CaCO₃ $\to$CaO + CO₂

2. 2H₂ + O₂ $\to$2H₂O

3. Na + H₂O $\to$ NaOH + \(\frac{1}{2}\)H₂

4. MnCl₃ $\to$ MnCl₂ + \(\frac{1}{2}\)Cl₂

Fluorine reacts with ice as per the following reaction

H₂O(s) + F₂(g) → HF(g) + HOF(g)

This reaction is a redox reaction because-

Which element exhibits both positive and negative oxidation states?