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

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

$20 \, mL$ of a solution of a weak monobasic acid neutralizes $22.18 \, mL$ of a solution of $NaOH$,and $20 \, mL$ of $N/10$ $HCl$ neutralizes $21.5 \, mL$ of the same $NaOH$ solution. The normality of the acid is nearly $.......$ $N$.

$A$ $2.0 \, g$ sample containing $MnO_2$ is treated with $HCl$ liberating $Cl_2$. The $Cl_2$ gas is passed into a solution of $KI$ and $60.0 \, mL$ of $0.1 \, M \, Na_2S_2O_3$ is required to titrate the liberated iodine. The percentage of $MnO_2$ in the sample is $.....$ (Nearest integer).
[Atomic masses (in $u$): $Mn = 55, Cl = 35.5, O = 16, I = 127, Na = 23, K = 39, S = 32$]

The primary standard solution for the estimation of $Na_2S_2O_3$ is:

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