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

The oxidation number of carbon in C₃O₂  and Mg₂C₃ are respectively:

1. -4/3, +4/3 

2. +4/3, -4/3

3. -2/3, +2/3

4. -2/3, +4/3

Which is the correct set that can only act as an oxidant? 

In the given reaction,

xBrO_3^- + yCr⁺³ + zH₂O $\to$Br₂ + CrO₄^2- + H⁺

The coefficients x, y, and z are respectively-

1. 6, 10, 11

2. 6, 10, 20

3. 6, 8, 22

4. 6, 10, 22

In the following reaction

Al + Fe₃O₄ $\to$Al₂O₃ + Fe

The total number of electrons transferred will be-

1. 6

2. 8

3. 8/3

4. 24

The oxidation number of S in H₂S₂O₈ is:

1. + 2

2. + 4

3. + 6

4. + 7

 The strongest oxidising agent among the following is -

1. $Br{O}_3^{-}/B{r}^{2+},E^o=+1.50$

2. $F{e}^{3+}/F{e}^{2+},E^o=+0.76$

3. $Mn{O}_4^{-}/M{n}^{2+},E^o=+1.52$

4. $C{r}_2{O}_7^{2-}/C{r}^{3+},E^o=+1.33$

Oxidation number of oxygen in potassium super oxide (KO₂) is-

1. – 2

2. – 1

3. – 1/2

4. – 1/4

For the redox reaction,
 a${\mathrm{MnO}}_4^{-}+{\mathrm{bC}}_2{\mathrm{O}}_4^{2-}+{\mathrm{cH}}^{+}\to {\mathrm{dMn}}^{2+}+{\mathrm{eCO}}_2+{\mathrm{fH}}_2\mathrm{O}$
the correct stoichiometric coefficients of the reactants a, b, and c respectively for the balanced equation are: 

1. 16, 5, 2
2. 2, 5, 16
3. 2, 16, 5
4. 5, 16, 2

The change in oxidation number of chlorine when Cl₂ gas reacts with hot and concentrated sodium hydroxide solution is:

1. Zero to +1 and Zero to –5

2. Zero to –1 and Zero to +5

3. Zero to –1 and Zero to +3

4. Zero to +1 and Zero to –3