JEE Main · 2021 · 26 Feb 2021 · Shift 1 · Practical and Analytical Chemistry

In the Carius method the organic compound is heated with fuming nitric acid and silver nitrate in a sealed hard glass tube; the halogen is precipitated as silver halide, and the same sealed tube serves for sulphur, precipitated as barium sulphate, and for phosphorus. Nitrogen is never estimated this way: it is determined by Dumas' method, which measures the nitrogen gas liberated, or by Kjeldahl's method, in which the nitrogen is converted to ammonium sulphate and the ammonia distilled into standard acid.
The phosphorus of an organic compound is oxidised to phosphoric acid and thrown down with magnesia mixture as magnesium ammonium phosphate, which on ignition leaves $\mathrm{M}{\mathrm{g}}_2{\mathrm{P}}_2{\mathrm{O}}_7$.
The false statement is the one claiming that the Carius method is used for the estimation of nitrogen.