Which of the following reduces Tollen's reagent?

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:

When ethane-$1, 2$-dioic acid is heated with conc. $H_2SO_4$,it gives

Which of the following reagents is used to obtain acetic anhydride from acetyl chloride?

In esterification,the $OH^-$ ion for making $H_2O$ comes from

Consider the acidity of the following carboxylic acids:
$(I)$ $PhCOOH$
$(II)$ $o-NO_2C_6H_4COOH$
$(III)$ $p-NO_2C_6H_4COOH$
$(IV)$ $m-NO_2C_6H_4COOH$
Which of the following is the correct order of acidity?