Question

 Acetone, Acetaldehyde, Benzaldehyde, Acetophenone – reactivity towards addition of HCN. 

Answer 1

Acetone, acetaldehyde, benzaldehyde, acetophenone - Reactivity with HCN 
\[\begin{array}{c}\ce{CH3-C-CH3}\\\ce{||}\\\ce{O}\end{array}
\begin{array}{c}\ce{CH3-CHO}\\\ce{||}\\\ce{O}\end{array}\ce{C6H5CHO}\begin{array}{c}\ce{CH3-C-C6H5}\\\ce{||}\\\ce{O}\end{array}\] 
Nucelophile addition by HCN is strongest for aldehyde than ketones. Also, acetophenone is more sterically hindered than acetone, hence comparatively less nucleophilic similarly C₆ H₅CHO i -s less reactive towards nucleophilic addition than CH₃CHO. 

\[\begin{array}{c}\ce{CH3-C-C6H5}\\\ce{||}\\\ce{O}\end{array}
\begin{array}{c}\ce{< CH3-C  -CH3}\\\ce{||}\\\ce{O}\end{array}\ce{<C6H5CHO < CH3CHO}\]