Q58 / 180 · COMEDK 2023 (Evening Shift) · Chemistry
Identify the correct statement describing the characteristics of $\mathrm{C}_2$ molecule.
- Correct answerABond order $=2.0 ; \quad$ Diamagnetic in nature; Both bonds formed are pi bonds.
- BBond order $=1.5 ; \quad$ Paramagnetic in nature; Both bonds formed are sigma bonds $(\sigma)$.
- CBond order $=0 \quad \mathrm{C}_2$ molecule is non-existent.
- DBond order $=2.0 ; \quad$ Paramagnetic in nature; One sigma and one pi bond formed.
Solution
$C_2$ (12e): $\sigma_{1s}^2 \sigma_{1s}^{*2} \sigma_{2s}^2 \sigma_{2s}^{*2} \pi_{2p_x}^2 \pi_{2p_y}^2$
Bond order $= \dfrac{1}{2}(8 - 4) = 2.0$
All electrons are paired $\to$ diamagnetic.
The two highest occupied MOs are $\pi_{2p_x}$ and $\pi_{2p_y}$ $\to$ both bonds formed are pi bonds.
Answer: Bond order $= 2.0$, diamagnetic, both bonds are pi bonds. Option (1)
Bond order $= \dfrac{1}{2}(8 - 4) = 2.0$
All electrons are paired $\to$ diamagnetic.
The two highest occupied MOs are $\pi_{2p_x}$ and $\pi_{2p_y}$ $\to$ both bonds formed are pi bonds.
Answer: Bond order $= 2.0$, diamagnetic, both bonds are pi bonds. Option (1)
Hence, the correct answer is option: 'A'.