What is obtained when $(CH_3)_2NCOCH_3$ is refluxed with acid?

What happens when $2-$hydroxybenzoic acid is distilled with zinc dust? It gives:

Which of the following compounds has the maximum acidic strength?

The decreasing order of acidic strength for the following acids is:
$(A)$ $CH_3COOH$
$(B)$ $CH_3CHClCH_2COOH$
$(C)$ $ClCH_2COOH$
$(D)$ $Cl_2CHCOOH$

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:

Acetic acid reacts with $PCl_5$ to form