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

$O\left( g \right) + {e^ - } \to O_{\left( g \right)}^ - \,\,\,\,;\,\,\,\,{\Delta _f}{H^\Theta } =  - 141\,kJ\,mo{l^{ - 1}}$

${O^ - }\left( g \right) + {e^ - } \to O_{\left( g \right)}^{2 - }\,\,\,\,;\,\,\,\,{\Delta _f}{H^\Theta } =  + 780\,kJ\,mo{l^{ - 1}}$

Thus process of formation of $O_2^-$ in gas phase is unfavourable even thought $O_2^-$ is isoelectronic with neon. It is due to the fact that,

$MgO(s) + C(s) \to Mg(s) + CO(g)$, for which $\Delta _r{H^o} =  + 491.1\,kJ\,mo{l^{ - 1}}$ and $\Delta _r{S^o} =  198.0\,Jk^{-1}\,mo{l^{ - 1}}$ is not feasible at $298\, K$. Temperature above which reaction will be feasible is.....$K$

If $T _2> T _1$, the correct statement(s) is (are)

(Assume $\Delta H ^{\ominus}$ and $\Delta S ^{\ominus}$ are independent of temperature and ratio of $\ln K$ at $T _1$ to $\ln K$ at $T_2$ is greater than $T_2 / T_1$. Here $H, S, G$ and $K$ are enthalpy, entropy, Gibbs energy and equillibrium constant, respectively.)

$(A)$ $\Delta H ^{\ominus}<0, \Delta S ^{\ominus}<0$  $(B)$ $\Delta G ^{\ominus}<0, \Delta H ^{\ominus}>0$  $(C)$ $\Delta G ^{\ominus}<0, \Delta S ^{\ominus}<0$  $(D)$ $\Delta G ^{\ominus}<0, \Delta S ^{\ominus}>0$

$Sn{O_2}(s) + 2{H_2}\left( g \right) \rightleftharpoons 2{H_2}O\left( g \right) + Sn\left( l \right)$

At equilibrium, the mixture of steam and hydrogen contains $40\%$ $H_2$ by volume then find $K_p$ for the reaction