A set of species capable of showing disproportionation reactions is:

1.	ClO-2, ClO-3, ClO-4, Cl2
2.	Cl2, ClO-2, ClO-3, S8
3.	ClO-4, ClO-, ClO-2, F2
4.	ClO-3, ClO-4, H2O2, ClO-

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

1. $\mathrm{Fe}+2\mathrm{HCl}\to {\mathrm{FeCl}}_2+{\mathrm{H}}_2\uparrow$

2. $2\mathrm{Pb}{\left({\mathrm{NO}}_3\right)}_2\to 2\mathrm{PbO}+4{\mathrm{NO}}_2+{\mathrm{O}}_2\uparrow$

3. $2{\mathrm{KClO}}_3\stackrel{∆}{\to }2\mathrm{KCl}+3{\mathrm{O}}_2$

4. ${\mathrm{Cr}}_2{\mathrm{O}}_3+2\mathrm{Al}\stackrel{∆}{\to }{\mathrm{Al}}_2{\mathrm{O}}_3+2\mathrm{Cr}$

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:

$F{e}^{+2}/Fe$ ,$E°$ $=$ $-0.\mathrm{44 }$

$\mathrm{ }F{e}^{+3}/F{e}^{+2} ,E°$ $=0.77$

Choose the correct observation if $F{e}^{+2},$ $F{e}^{+3}$, and Fe  block 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: