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

Estimation of $CO$ is done by using:

Identify the correct statements:
$A$. Hydrated salts can be used as primary standard.
$B$. Primary standard should not undergo any reaction with air.
$C$. Reactions of primary standard with another substance should be instantaneous and stoichiometric.
$D$. Primary standard should not be soluble in water.
$E$. Primary standard should have low relative molar mass.
Choose the correct answer from the options given below :

In the standardization of $Na_2S_2O_3$ using $K_2Cr_2O_7$ by iodometry,the equivalent weight of $K_2Cr_2O_7$ is

$2.52 \ g$ of oxalic acid dihydrate was dissolved in $100 \ mL$ of water. $10 \ mL$ of this solution was diluted to $500 \ mL$. The normality of the final solution (in $N$) and the amount of oxalic acid (in $mg/mL$) in the solution are respectively

Which of the following statements is not true about Mohr's salt?