Which compound gives acetaldehyde upon reaction with aqueous $KOH$?

The final product obtained by distilling ethyl alcohol with an excess of chlorine and $Ca(OH)_2$ is:

Consider the reaction sequence shown below:
$Br-CH_2-CHO$ $\xrightarrow[\text{dry } HCl \text{ gas}]{\text{EtOH (excess)}} A$ $\xrightarrow{^tBuO^-K^+} B$
[Where $Et \Rightarrow -C_2H_5$,$^tBu \Rightarrow (CH_3)_3C^-$]
Identify the major products $A$ and $B$ formed respectively.

What is retention and inversion of configuration? Explain with suitable examples.

The product of which of the following reactions undergoes hydrolysis by the $S_N 1$ mechanism?

Identify $Z$ in the following series of reactions: