What does the product obtained from the reaction of acetaldehyde with $HCN$ followed by hydrolysis exhibit?

When carboxylic acid is treated with chlorine in the presence of red phosphorus,an alpha-chloro acid is formed. This reaction is known as:

The following species are involved in the formation of an ester from a carboxylic acid in the presence of acid. The correct sequence of formation of these species is

Formic acid on heating with concentrated $H_2SO_4$ at $373 \ K$ gives $X$,a colourless substance and $Y$,a good reducing agent. The number of $\sigma$ and $\pi$ bonds in $X$ and $Y$ are respectively:

Identify the structure of product $A$ in the following reaction:
$\text{Cyclohexanecarboxylic acid} \xrightarrow{LiAlH_4} A$

The correct order of decreasing acid strength of trichloroacetic acid $(A)$,trifluoroacetic acid $(B)$,acetic acid $(C)$,and formic acid $(D)$ is