Which structure has delocalised $\pi$-electrons?

• Correct answer
  A

  $\mathrm{O}_{3}$
• B

  $\mathrm{CO}$
• C

  $\mathrm{HCN}$
• D

  $\mathrm{O}_{3}$ and $\mathrm{HCN}$

Solution

$\mathrm{O}_{3}$ (ozone) has delocalised $\pi$ electrons

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