The reaction $CH_3COOH + Cl_2 \xrightarrow{P} ClCH_2COOH + HCl$ is called

In the following transformation,reagents $1$ and $2$ are:

Which of the following is the correct order of acidic strength?

When carboxylic acid reacts with organolithium reagents to give ketones,side reactions sometimes occur. For example,
$HOCH_2CH_2CH(CH_3)CH_2CH_2COOH$ $\xrightarrow[(x) \, CH_3Li]{tetrahydro\,furan}$ $\xrightarrow[NH_4Cl]{H_2O}$ $\underset{63\%}{\text{Compound } A: HOCH_2CH_2CH(CH_3)CH_2CH_2COCH_3}$ + $\underset{37\%}{\text{Compound } (B)}$
The value of $(x)$ in the above reaction is:

The order of acidity of compounds $I-IV$ 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: