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

When nitrogen gas is passed through $100 \ mL$ of $0.1 \ M$ $H_2SO_4$ containing $0.30 \ g$ of an organic compound,the ammonia evolved is neutralized. To neutralize the excess acid,$20 \ mL$ of $0.5 \ M$ $NaOH$ is required. Identify the organic compound.

Which of the following cannot give iodometric titrations?

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:

Which of the following reagents is not used in qualitative and quantitative chemical analysis?

Iodine and hypo react to produce