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

The weight of potassium dichromate (molecular weight $= 294$) required to prepare $250 \ mL$ of $0.04 \ N$ solution is (in $g$)

$100 \ mL$ of aqueous solution of $0.05 \ M$ $Cu^{2+}$ is added to $1 \ L$ of $0.1 \ M$ $KI$ solution. The resultant solution was titrated with $0.01 \ M$ $Na_2S_2O_3$ solution using starch indicator till blue color disappeared. What is the volume (in $mL$) of $Na_2S_2O_3$ used?

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

$10 \ cm^{3}$ of $0.1 \ N$ monobasic acid requires $15 \ cm^{3}$ of sodium hydroxide solution whose normality is: (in $N$)

$10 \, mL$ of concentrated $HCl$ were diluted to $1 \, L$. $20 \, mL$ of this diluted solution required $25 \, mL$ of $0.1 \, N$ sodium hydroxide solution for complete neutralization. The normality of the concentrated hydrochloric acid will be: