Acetaldehyde cannot show:

Identify the product of the following reaction: $Formaldehyde + Benzaldehyde \xrightarrow[H_3O^{+}]{conc. NaOH} \text{product}$

Identify the final product $D$ in the given reaction sequence:
$CH_3CH_2Cl$ $\xrightarrow{Aq. KOH} A$ $\xrightarrow{PCC} B$ $\xrightarrow{Cl_2/NaOH} C$ $\xrightarrow{Acetone} D$
Product $D$ is known as:

$CH_3-CO-CH_3$ $\xrightarrow{I_2/NaOH} \underset{\text{yellow compound}}{(A)} + (B)$ $\xrightarrow{Ag - \text{powder}, \Delta} (C)$ $\xrightarrow{Dil. H_2SO_4/HgSO_4} (D)$
$A, C$ and $D$ are :-

The starting material is $2,3-\text{dimethylbut-2-ene}$. It undergoes ozonolysis followed by reduction with $Zn/H_2O$ to form product $A$. Product $A$ then reacts with $CH_3MgBr$ followed by hydrolysis to form product $B$. Identify product $B$.

Write a note on the addition of hydrogen cyanide to aldehydes and ketones.