$2 \mathrm{H}_{2} \mathrm{O} \rightarrow \mathrm{O}_{2}+4 \mathrm{H}^{\oplus}+4 \mathrm{e}^{-} ; \mathrm{E}_{\mathrm{red}}^{0}=1.23 \mathrm{V}$ અને $ - 5 \times {10^{ - 4}}\,V\,{K^{ - 1}}$ છે. કોષપ્રક્રિયા $(\mathrm{R}=8.314 \;\mathrm{J} \mathrm{mol}^{-1} \mathrm{K}^{-1} ; \text { Temperature }=298 \;\mathrm{K} ;$ ઓક્સિજન એ પ્રમાણિત વાતાવરણ દબાણ $1$ બાર હેઠળ છે)
$\mathrm{O}_{2}(\mathrm{g})+4 \mathrm{H}^{+}+4 \mathrm{e}^{-} \rightarrow 2 \mathrm{H}_{2} \mathrm{O}(l) ; \mathrm{E}_{\mathrm{red.}}^{0}=1.23 \mathrm{V}$
From nernst equation
$\mathrm{E}_{\text {cell }}=\mathrm{E}_{\text {cell }}^{0}-\frac{\mathrm{RT}}{\mathrm{nF}} \ln \mathrm{Q}$
at $1\; bar$ and $298 \mathrm{K}$
$\frac{2.303 \mathrm{RT}}{\mathrm{F}}=0.059$
$\mathrm{pH}=5 \Rightarrow\left[\mathrm{H}^{+}\right]=10^{-5} \mathrm{M}$
$\mathrm{E}_{\text {cell }}=1.23-\frac{0.059}{4} \log \left[\mathrm{H}^{+}\right]^{4}$
$\mathrm{E}_{\text {cell }}=1.23-\frac{0.059}{4} \log \left(10^{-5}\right)^{4}$
$=1.23+0.295=1.525 \mathrm{V}$
$Zn^{+2}_{(aq)} + 2e \rightleftharpoons Zn(s), -0.76\,\, volt$ ;
$Ce^{+3}_{(aq)} + 3e \rightleftharpoons Cr(s), -0.74 \,\,volt.$
$2H^{+2}_{(aq)} + 2e \rightleftharpoons H_2(g), + 0.0\,volt$ ;
$Fe^{+3}_{(aq)} + e \rightleftharpoons Fe^{+2}_{(aq)}, + 0.77 \,\,volt$
નીચેનામાંથી કયો પ્રબળ રીડ્યુસીંગ એજન્ટ છે ?
$Z{n^{2 + }}(aq.) + 2e$ $\rightleftharpoons$ $Zn(s)$; $→$ $-0.762$
$C{r^{3 + }}(aq) + 3e$ $\rightleftharpoons$ $Cr(s)$; $→$ $ -0.740$
$2{H^ + }(aq) + 2e$ $\rightleftharpoons$ ${H_2}(g)$; $→$ $0.00$
$F{e^{3 + }}(aq) + e$ $\rightleftharpoons$ $F{e^{2 + }}(aq)$; $→$ $0.770$
નીચે પૈકી કયું પ્રબળ રીડકશનકર્તા છે?