The acid having the highest $pK_a$ value among the following is

What is the product formed when acetic acid reacts with chlorine in the presence of an anhydrous $FeCl_3$ catalyst?

The descending order of acidity for the following carboxylic acids is:
$A.$ $CH_3COOH$
$B.$ $F_3C-COOH$
$C.$ $ClCH_2-COOH$
$D.$ $FCH_2-COOH$
$E.$ $BrCH_2-COOH$
Choose the correct answer from the options given below:

$CH_2=CH-CO-OCH_3$ (methyl acrylate,bp $81^\circ C$) + $CH_3-CH_2-CH_2-CH_2-OH$ (n-butyl alcohol,bp $117^\circ C$) $\xrightarrow{TsOH, \Delta} (A)$ (bp $145^\circ C$) + $CH_3OH$ (bp $65^\circ C$). Product $(A)$ of the above reaction is:

$4$-Pentenoic acid when treated with $I_2$ and $NaHCO_3$ gives:

On heating acetamide in the presence of $P_2O_5$,which of the following is formed?