With $63 \ g$ of oxalic acid,how many litres of $\frac{N}{10}$ solution can be prepared?

Why is it essential to wash the precipitate with water before estimating it quantitatively?

Estimation of $CO$ is done by using:

During the preparation of Mohr's salt solution (Ferrous ammonium sulphate),which of the following acid is added to prevent hydrolysis of $Fe^{2+}$ ion?

Given below are two statements
Statement $I$: Aqueous solution of $K_2Cr_2O_7$ is preferred as a primary standard in volumetric analysis over $Na_2Cr_2O_7$ aqueous solution.
Statement $II$: $K_2Cr_2O_7$ has a higher solubility in water than $Na_2Cr_2O_7$.
In the light of the above statements,choose the correct answer from the options given below:

The disodium salt of ethylene diamine tetraacetic acid can be used to estimate the following ion$(s)$ in an aqueous solution: