Question

The decreasing order of aromaticity of the following is :
$I.$ Benzene $II.$ Naphthalene $III.$ Anthracene

• A. $\left(I\right)>\left(II\right)>\left(III\right)$
• B. $\left(III\right)>\left(II\right)>\left(I\right)$
• C. $\left(II\right)>\left(I\right)>\left(III\right)$
• D. $\left(II\right)>\left(III\right)>\left(I\right)$

Answer 1

Answer: (A)

$\left(I\right)>\left(II\right)>\left(III\right)$

R.E of benzene, naphthalene and anthracene, respectively are $151,255$ and $351kJ$ ${mol}^{-1}$.

R.E/ring of naphthalene (two rings)$=255/2=127.5kJ$ ${mol}^{-1}$
R.E/ring of anthracene (three rings)$=351/3=117kJ$ ${mol}^{-1}$

On the basis of R.E/ring, R.E of benzene > naphthalene > anthracene.

Hence, more stable the ring (more R.E/ring), more is the aromatic character.

Option A is correct.