Which of the following compounds contains iron (Fe) in the zero oxidation state?

1.	[Fe(CN)6]-4	2.	[Fe(CN)6]-3
3.	Fe(CO)5	4.	All of the above.

Which of the following best describes the behavior of bromine in the given reaction?

${\mathrm{H}}_2\mathrm{O}+{\mathrm{Br}}_2\to \mathrm{HOBr}+\mathrm{HBr}$

1. Both oxidized and reduced

2. Oxidized only

3. Reduced only

4. Proton acceptor only

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

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

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

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