STD 11 -p-Block elements - I — JEE STD 11 Science — Question

$Pt(s) |H_2(g)\,|\,HCOOH(aq.)\,||\,CH_3COOH(aq.)\,|\,H_2(g)|Pt(s)$
at $25\,^o C$ is ............ $\mathrm{V}$

$(K_a$ of  $HCOOH \,= 2.4 × 10^{-4}$  , $K_a$ of $CH_3COOH = 1.8 × 10^{-5}$ , $log\,2\, = 0.3,\, log \,0.48, \frac{2.303 \times 298 \times R}{F} = 0.06)$

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Pre-exponential factors for the forward and backward reactions are $10^{15} \mathrm{~s}^{-1}$ and $10^{11} \mathrm{~s}^{-1}$, respectively. If the value of $\log \mathrm{K}$ for the reaction at $500 \mathrm{~K}$ is $6$ , the value of $\left|\log \mathrm{k}_{\mathrm{b}}\right|$ at $250 \mathrm{~K}$ is $\qquad$

$[\mathrm{K}=$ equilibrium constant of the reaction

$\mathrm{k}_{\mathrm{f}}=$ rate constant of forward reaction

$\mathrm{k}_{\mathrm{b}}=$ rate constant of backward reaction]

Statement $I$: $\mathrm{S}_8$ solid undergoes disproportionation reaction under alkaline conditions to form $\mathrm{S}^{2-}$ and $\mathrm{S}_2 \mathrm{O}_3{ }^{2-}$

Statement $II$: $\mathrm{ClO}_4^{-}$can undergodisproportionation reaction under acidic condition. In the light of the above statements, choose the most appropriate answer from the options given below :