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 correct structure of tribromo octoxide is:

1.
2.
3.
4.

Disproportionation reactions are:

(a) $2{\mathrm{Cu}}^{+}$ $\to$ ${\mathrm{Cu}}^{2+}+{\mathrm{Cu}}^0$

(b) $3{\mathrm{MnO}}_4^{2-}+4{\mathrm{H}}^{+}$ $\to$ $2{\mathrm{MnO}}_4^{-}+{\mathrm{MnO}}_2+2{\mathrm{H}}_2\mathrm{O}$

(c) $2{\mathrm{KMnO}}_4$ $\stackrel{∆}{\to }$ ${\mathrm{K}}_2{\mathrm{MnO}}_4+{\mathrm{MnO}}_2+{\mathrm{O}}_2$

(d) $2{\mathrm{MnO}}_4^{-}+3{\mathrm{Mn}}^{2+}+2{\mathrm{H}}_2\mathrm{O}$ $\to$ $5{\mathrm{MnO}}_2+4{\mathrm{H}}^{\oplus }$

1. (a) and (d) only

2. (a) and (b) only

3. (a), (b) and (c)

4. (a), (c) and (d)