Which among the following are having diamagnetic property? (i) $\mathrm{B}_2$ (ii) $\mathrm{N}_2$ (iii)…

Which among the following are having diamagnetic property? (i) $\mathrm{B}_2$ (ii) $\mathrm{N}_2$ (iii) $\mathrm{O}_2$ (iv) $\mathrm{C}_2$
  1. ii, iii
  2. i, iv
  3. ii, iv
  4. i, ii

Solution

Molecular orbital configuration for (i) $\mathrm{B}_2(10)=\sigma 1 s^2, \sigma^* 1 s^2, \sigma 2 s^2, \sigma^* 2 s^2, \pi p_x^1 \approx \pi p_y^1$ Two unpaired electrons, paramagnetic. (ii) $\mathrm{N}_2(14)$ $ =\sigma 1 s^2, \sigma^* 1 s^2, \sigma 2 s^2, \sigma * 2 s^2, \pi p_x^2 \approx \pi p_y^2, \sigma 2 p_z^2 $ No unpaired electrons, diamagnetic. (iii) $\mathrm{O}_2(16)$ $ \begin{aligned} = & \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 \\ & \pi * 2 p_x^1, \pi * 2 p_y^1 \end{aligned} $ Two unpaired electrons, paramagnetic (iv) $\mathrm{C}_2(12)$ $ =\sigma 1 s^2, \sigma * 1 s^2, \sigma 2 s^2, \sigma * 2 s^2, \pi 2 p_x^2 \approx \pi 2 p_y^2 $ No unpaired electron, diamagnetic

Asked in: AP EAMCET 2017 (26 Apr Shift 1)

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