$1$ mole of $PbS$ is oxidised by "$X$" moles of $O_3$ to get "$Y$" moles of $O_2$. $X + Y = $ . . . . . . .

Which of the following is a redox reaction?
$(i) \, CdCl_2 + 2 KOH \longrightarrow Cd(OH)_2 + 2 KCl$
$(ii) \, BaCl_2 + K_2SO_4 \longrightarrow BaSO_4 + 2 KCl$
$(iii) \, CaCO_3 \longrightarrow CaO + CO_2$
$(iv) \, 2 Ca + O_2 \longrightarrow 2 CaO$

$KMnO_4$ oxidises oxalic acid to $CO_2$ in acidic medium. The equivalent weight of $KMnO_4$ is $(Mn = 55, K = 39, O = 16)$:

$C +$ Conc. $H_2SO_4 \xrightarrow{\Delta} X + Y + H_2O$. $X$ and $Y$ in the above reaction are:

Explain intermolecular redox reaction with an example.

$Na_2S_2O_3 + I_2 \to$ Product is