Acetone and acetaldehyde are differentiated by

The increasing order of the rate of $HCN$ addition to the following compounds is:
$(A)\ HCHO$
$(B)\ CH_3COCH_3$
$(C)\ PhCOCH_3$
$(D)\ PhCOPh$

End products of the following sequence of reactions are:

Identify product $B$ in the following reaction: $\text{Propanone}$ $\xrightarrow{\text{Ba(OH)}_2} A$ $\xrightarrow{\Delta, -\text{H}_2\text{O}} B$

In the reaction scheme shown below,$Q$,$R$,and $S$ are the major products. Identify the correct structure of the products from the given options:
$(P)$ + Succinic anhydride $\xrightarrow{AlCl_3}$ $Q$
$Q$ $\xrightarrow[H_3PO_4]{Zn-Hg/HCl}$ $R$
$R$ $\xrightarrow[(ii) H_3O^+]{(i) CH_3MgBr, (iii) H_2SO_4/\Delta}$ $S$
$(A)$ $S$ is [Structure $A$]
$(B)$ $Q$ is [Structure $B$]
$(C)$ $R$ is [Structure $C$]
$(D)$ $S$ is [Structure $D$]

The major product of the following reaction sequence is: