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

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

Which of the following cannot give iodometric titrations?

The ammonia evolved from the treatment of $0.30 \, g$ of an organic compound for the estimation of nitrogen was passed in $100 \, mL$ of $0.1 \, M$ sulphuric acid. The excess of acid required $20 \, mL$ of $0.5 \, M$ sodium hydroxide solution for complete neutralization. The organic compound is:

$10 \, mL$ 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:

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