The Lassaigne's extract is boiled with conc. $HNO_3$ while testing for halogens. By doing so it

Which of the following nitrogen-containing compounds does not give Lassaigne's test?

Which of the following methods is used to check the purity of an organic compound?

In the Lassaigne's test,the Prussian blue precipitate is formed due to the formation of which compound?

Given below are two statements :
Statement $I$ : Nitrogen,sulphur,halogen and phosphorus present in an organic compound are detected by Lassaigne's Test.
Statement $II$ : The elements present in the compound are converted from covalent form into ionic form by fusing the compound with Magnesium in Lassaigne's test.
In the light of the above statements,choose the correct answer from the options given below :

Name the methods used for determining the molecular mass of organic compounds.