Chemical reaction between quick lime and water is characterised by

A science teacher wrote the following statements about rancidity:

$\left(\mathrm{i}\right)$ When fats and oils are reduced, they become rancid.

$\left(\mathrm{ii}\right)$ In chips packet, rancidity is prevented by oxygen.

$\left(\mathrm{iii}\right)$ Rancidity is prevented by adding antioxidants.

Select the correct option.

Which on of the following is an example of a redox reaction?

Classify each of the following reactions:

$$\begin{gathered} \mathrm{Zn}\left(\mathrm{s}\right)+2{\mathrm{AgNO}}_3\left(\mathrm{aq}\right)\to \mathrm{Zn}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{aq}\right)+2\mathrm{Ag}\left(\mathrm{s}\right) \\ \mathrm{Ca}{\left(\mathrm{OH}\right)}_2\left(\mathrm{s}\right)\stackrel{∆}{\to }\mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right) \\ \mathrm{Cu}{\left({\mathrm{NO}}_3\right)}_2\left(\mathrm{aq}\right)+2{\mathrm{Na}}_2\mathrm{S}\left(\mathrm{aq}\right)\to \mathrm{CuS}\left(\mathrm{s}\right)+2{\mathrm{NaNO}}_3\left(\mathrm{aq}\right) \\ {\mathrm{H}}_2{\mathrm{SO}}_3\left(\mathrm{aq}\right)+2\mathrm{KOH}\left(\mathrm{aq}\right)\to {\mathrm{K}}_2{\mathrm{SO}}_3\left(\mathrm{aq}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \end{gathered}$$

$\mathrm{P}, \mathrm{Q},$ and $\mathrm{R}$ are three metals that undergo chemical reactions as follows:
$$\begin{gathered} {\mathrm{P}}_2{\mathrm{O}}_3+2\mathrm{Q}\to {\mathrm{Q}}_2{\mathrm{O}}_3+2\mathrm{P} \\ 2\mathrm{P}+3\mathrm{RO}\to {\mathrm{P}}_2{\mathrm{O}}_3+3\mathrm{R} \\ 3{\mathrm{RSO}}_4+2\mathrm{Q}\to {\mathrm{Q}}_2{\left({\mathrm{SO}}_4\right)}_3+3\mathrm{R} \end{gathered}$$

Observe the reactions and arrange the metals in the increasing order of their reactivity.