$K_2Cr_2O_7$ is preferred to $Na_2Cr_2O_7$ for use in volumetric analysis as a primary standard because

What weight of ferrous ammonium sulphate is needed to prepare $100 \, mL$ of $0.1 \, N$ solution? (mol. wt. $392$)

The functional groups that are responsible for the ion-exchange property of cation and anion exchange resins,respectively,are :

Which of the following reagents is not used in qualitative and quantitative chemical analysis?

$A$ $0.166 \ g$ sample of an organic compound was digested with conc. $H_2SO_4$ and then distilled with $NaOH$. The ammonia gas evolved was passed through $50.0 \ mL$ of $0.5 \ N \ H_2SO_4$. The excess acid required $30.0 \ mL$ of $0.25 \ N \ NaOH$ for complete neutralization. The mass percentage of nitrogen in the organic compound is $..... \ \%$.

Identify the incorrect statements regarding primary standard of titrimetric analysis.
$(A)$ It should be purely available in dry form.
$(B)$ It should not undergo chemical change in air.
$(C)$ It should be hygroscopic and should react with another chemical instantaneously and stoichiometrically.
$(D)$ It should be readily soluble in water.
$(E)$ $KMnO_4$ and $NaOH$ can be used as primary standard.
Choose the correct answer from the options given below: