Q24 / 180 · COMEDK 2018 · Chemistry

Which of the following has the highest bond order?

  • Correct answer
    A
    $\mathrm{N}_{2}$
  • B
    $\mathrm{O}_{2}$
  • C
    $\mathrm{He}_{2}$
  • D
    $\mathrm{H}_{2}$

Solution

$\mathrm{N}_{2}$ [14 electrons $]=$ $\sigma 1 s^{2}, \sigma^{\circ} 1 s^{2}, \sigma 2 s^{2}, \sigma^{*} 2 s^{2}, \pi 2 p_{x}^{2}=\pi 2 p_{y}^{2}, \sigma 2 p_{z}^{2}$ Bond order $=\frac{N_{b}-N_{a}}{2}\left[\begin{array}{l}N_{b} \text { and } N_{a} \text { are bonding and } \\ \text { anti bonding molecular } \\ \text { orbital } s \text { - electron }\end{array}\right]$ $=\frac{10-4}{2}=3$ $\therefore \mathrm{N}_{2}$ has highest bond order i.e. 3 . While $\mathrm{O}_{2}, \mathrm{He}_{2}$ and $\mathrm{H}_{2}$ have 2,0 and $1 / 2$ bond order respectively.

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

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