At \(298 {~K},\) the standard electrode potentials of \(\mathrm{{Cu}^{2+} /{Cu},}\) \(\mathrm{{Zn}^{2+} / {Zn},~~ {Fe}^{2+} / {Fe}}\) and \(\mathrm{{Ag}^{+} / {Ag}} \) are \(\mathrm{0.34 {~V}, -0.76 {~V},}\)  \(\mathrm{-0.44 {~V}}\) and \(\mathrm{0.80 {~V},}\) respectively.
On the basis of standard electrode potentials, predict which of the following reaction can not occur?

1.	\(\mathrm{2 {CuSO}_{4}({aq})+2 {Ag}({s}) → 2 {Cu}({s})+{Ag}_{2} {SO}_{4}({aq})} \)
2.	\(\mathrm{{CuSO}_{4}({aq})+{Zn}({s})} \) \(\mathrm{→ {ZnSO}_{4}({aq})+{Cu}({s})} \)
3.	\(\mathrm{{CuSO}_{4}({aq})+{Fe}({s})} \) \(\mathrm{→ {FeSO}_{4}({aq})+{Cu}({s})} \)
4.	\(\mathrm{{FeSO}_{4}({aq})+{Zn}({s})} \) \(→ \mathrm{{ZnSO}_{4}({aq})+{Fe}({s})} \)

A set of species capable of showing disproportionation reactions is:

The correct example of metal displacement reaction among the following is:

The oxidation states(O.S.) of sulphur in the anions ${{\mathrm{SO}}_3}^{2-},$ ${\mathrm{S}}_2{{\mathrm{O}}_4}^{2-}$ $\mathrm{and}$ ${\mathrm{S}}_2{{\mathrm{O}}_6}^{2-}$ follow the order:

1. ${\mathrm{S}}_2{{\mathrm{O}}_4}^{2-}<{{\mathrm{SO}}_3}^{2-}<{\mathrm{S}}_2{{\mathrm{O}}_6}^{2-}$

2. ${{\mathrm{SO}}_3}^{2-}<{\mathrm{S}}_2{{\mathrm{O}}_4}^{2-}<{\mathrm{S}}_2{{\mathrm{O}}_6}^{2-}$

3. ${\mathrm{S}}_2{{\mathrm{O}}_4}^{2-}<{\mathrm{S}}_2{{\mathrm{O}}_6}^{2-}<{{\mathrm{SO}}_3}^{2-}$

4. ${\mathrm{S}}_2{{\mathrm{O}}_6}^{2-}<{\mathrm{S}}_2{{\mathrm{O}}_4}^{2-}<{{\mathrm{SO}}_3}^{2-}$

Standard electrode potentials are:

\(F e^{+ 2} / F e\) , \(E^\circ\) \(=\) \(- 0 .44\)

\(F e^{+ 3} / F e^{+ 2}\), \(E ^\circ\) \(= 0 . 77\)

Choose the correct observation when \(𝐹𝑒^{+2}\) ${\mathrm{}}^{}$, \(𝐹𝑒^{+3}\) and \(Fe_{(solid)}\) are kept together:

1. $F{e}^{+3}$ increases

2. $F{e}^{+3}$ decreases

3. $\frac{F{e}^{+2}}{F{e}^{+3}}$ remains unchanged

4. $F{e}^{+2}$ decreases

A non-feasible reaction among the following is:

1. $2$ $\mathrm{KI}+{\mathrm{Br}}_2\to 2\mathrm{KBr}+{\mathrm{I}}_2$

2. $2$ $\mathrm{KBr}+{\mathrm{I}}_2\to 2\mathrm{KI}+{\mathrm{Br}}_2$

3. $2$ $\mathrm{KBr}+{\mathrm{Cl}}_2\to 2\mathrm{KCl}+{\mathrm{Br}}_2$

4. $2{\mathrm{H}}_2\mathrm{O}+2{\mathrm{F}}_2\to 4\mathrm{HF}+{\mathrm{O}}_2$

If the oxidation numbers of A, B, and C are + 2, +5, and –2 respectively, then the possible formula of the compound is: