MCQ
The enthalpy of combustion of benzene from the following data will be

$(i)$ $6C(s) + 3{H_2}(g) \to {C_6}{H_6}(l);\,\Delta H = + 45.9\,kJ$

$(ii)$ ${H_2}(g) + \frac{1}{2}{O_2}(g) \to {H_2}O(l);\,\Delta H = - 285.9\,kJ$

$(iii)$ $C(s) + {O_2}(g) \to C{O_2}(g);\,\Delta H = - 393.5\,kJ$

........$kJ$

  • A
    $+ 3172.8$
  • B
    $-1549.2 $
  • C
    $-3172.8$
  • $-3264.6 $

Answer

Correct option: D.
$-3264.6 $
(d) Multiplying eq. $(ii)$ by $(iii)$ and eq. $(iii)$ by $(vi),$ and then add
$6\,C + 3{H_2} + \frac{{15}}{2}{O_2} \to $$6\,C{O_2} + 6{H_2}O;\,\,\Delta H = 3218.7$
Subtract eq. $(i)$ from the above equation and find the required result.

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