Which of the following species is/are planar? 

How many of the following are heterocyclic aromatic compounds? 

Benzene, cyclopentadiene, oxirane, tetrahydrofuran, naphthalene, cyclopentane, tropolone, azulene, diphenyl. 

How many of the following cannot show tautomerism? 

Acetophenone, acetaldehyde, cyclohexanone, acetylacetone, benzoquinone, acetone, benzaldehyde, butanone, ethyl acetoacetate. 

Amongst the following the total number of electrophiles is :

${\mathrm{CN}}^{-}, {\mathrm{H}}^{+}, {{\mathrm{NO}}_2}^{+}, {\mathrm{Cl}}^{+},{\mathrm{OH}}^{-}, {\mathrm{H}}_3{\mathrm{O}}^{+}, :{\mathrm{CH}}_2, :{\mathrm{NH}}_3, {\mathrm{Na}}^{+}$

Amongst the following the total number of nucleophiles is :

${\mathrm{SO}}_3, {{\mathrm{NH}}_2}^{-}, {\mathrm{R}}^{-}, {\mathrm{H}}_2\mathrm{O}, {\mathrm{OR}}^{-}, \mathrm{ROH}, {\mathrm{AlCl}}_3, {\mathrm{H}}^{-}, {\mathrm{BF}}_3$