Write the structures of the isomers of alcohols with molecular formula C₄H₁₀O. Which of these exhibits optical activity? 

This is a short answer type question as classified in NCERT Exemplar

The alcohol with molecular formula C₄H₁₀O is butanol has 4 isomers, these are:

(a) CH₃-CH₂CH₂-CH₂OH   (Butane-1-ol)

(b) CH₃-C^*H-CH₂-CH₃  (Butane-2-ol)

            |

          OH

(c) CH₃-CH-CH₂-OH         (2-methylpropane-1-ol)