Polymers — Chemistry STD 12 Science — Question

$H{_2(g)} + 2ICl_{(g)} \to 2HCl_{(g)} + I_{2(g)}$

This reaction is of first order with respect to $H_{2(g)}$ and $ICl_{(g)}$ , following mechanisms were proposed

Mechanism $A$ :

$H{_2(g)} + 2ICl_{(g)} \to 2HCl_{(g)} + I_{2(g)}$

Mechanism $B$ :

$H_{2(g)} + ICl_{(g)} \to HCl_{(g)} + HI_{(g)}$  ;   Slow

$HI_{(g)} + ICl_{(g)} \to HCl_{(g)} + I_{2(g)}$  ;  Fast

Which of the above mechanism $(s)$ can be consistent with the given information about the reaction

$E ^0\left( Fe ^{3+} . Fe ^{2+}\right)=+0.77 V $

$E ^0\left( Fe ^{2+} . Fe \right)=-0.44 V $

$E ^{\circ}\left( Cu ^{2+} . Cu \right)=+0.34 V $

$E ^0\left( Cu ^{+} . Cu \right)=+0.52 V $

$E ^{\circ}\left( O _2( g )+4 H ^{+}+4 e ^{-} \rightarrow 2 H _2 O \right)=+1.23 V $

$E ^{\circ}\left( O _2( g )+2 H _2 O +4 e ^{-} \rightarrow 4 OH \right)=+0.40 V $

$E ^0\left( Cr ^{3+} . Cr \right)=-0.74 V $

$E ^{\circ}\left( Cr ^{2+} . Cr \right)=-0.91 V$

Match $E ^{\circ}$ of the rebox pair in List $I$ with the values given in List $II$ and select the correct answer using the code given below the lists:

Codes: $ \quad P \quad Q \quad R \quad S $ 

Given $\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}, \log 4=0.6021$