$20 \ mL$ of $HCl$ solution requires $19.85 \ mL$ of $0.01 \ M$ $NaOH$ solution for complete neutralization. The molarity of $HCl$ solution is

$50 \ cm^{3}$ of $0.2 \ N \ HCl$ is titrated against $0.1 \ N \ NaOH$ solution. The titration was discontinued after adding $50 \ cm^{3}$ of $NaOH$. The remaining titration is completed by adding $0.5 \ N \ KOH$. The volume of $KOH$ required for completing the titration is (in $cm^{3}$)

$5.00 \ mL$ of $0.10 \ M$ oxalic acid solution taken in a conical flask is titrated against $NaOH$ from a burette using phenolphthalein indicator. The volume of $NaOH$ required for the appearance of permanent faint pink color is tabulated below for five experiments. What is the concentration,in molarity,of the $NaOH$ solution?

$Exp. \ No.$	$Vol. \ of \ NaOH \ (mL)$
$1$	$12.5$
$2$	$10.5$
$3$	$9.0$
$4$	$9.0$
$5$	$9.0$

An organic dye,eosin,used to detect the endpoint of precipitation titration by adsorption is called:

Which reagent is commonly used for the determination of water hardness by titration?

Compounds that should not be used as primary standards in titrimetric analysis are $:$
$A.$ $Na_2Cr_2O_7$
$B.$ Oxalic acid
$C.$ $NaOH$
$D.$ $FeSO_4 \cdot 6H_2O$
$E.$ Sodium tetraborate
Choose the most appropriate answer from the options given below $:$