From the following data at $25^{\circ} C$,calculate the $\Delta_{r} H^0$ for the reaction $H_2O_{(g)} \rightarrow 2 H_{(g)} + O_{(g)}$:
$1/2 H_{2(g)} + 1/2 O_{2(g)} \rightarrow OH_{(g)}$$\Delta H = 42.09 \ kJ \ mol^{-1}$
$H_{2(g)} + 1/2 O_{2(g)} \rightarrow H_2O_{(g)}$$\Delta H = -242 \ kJ \ mol^{-1}$
$H_{2(g)} \rightarrow 2 H_{(g)}$$\Delta H = 436 \ kJ \ mol^{-1}$
$O_{2(g)} \rightarrow 2 O_{(g)}$$\Delta H = 496 \ kJ \ mol^{-1}$

  • A
    $1174 \ kJ \ mol^{-1}$
  • B
    $742 \ kJ \ mol^{-1}$
  • C
    $926 \ kJ \ mol^{-1}$
  • D
    $690 \ kJ \ mol^{-1}$

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