Q18 / 160 · AP EAMCET 2012 · Chemistry

According to molecular orbital theory, the total number of bonding electron pairs in $\mathrm{O}_2$ is

  • A
    $2$
  • B
    $3$
  • Correct answer
    C
    $5$
  • D
    $4$

Solution

The molecular orbital electronic configuration of $\mathrm{O}_2$ is $\begin{aligned} & \mathrm{O}_2\left(8+8=16 e^{-}\right)=\sigma 1 s^2, \sigma 1 s^2, \sigma 2 s^2, \sigma^* 2 s^2, \\ & \sigma 2 p_z^2, \pi 2 p_x^2, \approx \pi 2 p_y^2, \stackrel{*}{\pi} 2 p_x^1 \approx \stackrel{*}{\pi} 2 p_y^1 \\ & \end{aligned}$ (Unstarred $\sigma$ and $\pi$ represent bonding orbitals.) $\therefore$ number of bonding electrons $=10$ and number of bonding electron pairs $=5$

Hence, the correct answer is option: 'C'.

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