Question:
Kjeldahl's method cannot be used to estimate nitrogen for which of the following compounds?
$\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NH}_{2}$
$\mathrm{CH}_{3} \mathrm{CH}_{2}-\mathrm{C} \equiv \mathrm{N}$
$\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{NO}_{2}$
Correct Option: , 3
Solution:
Kjeldahl's method can not be used for nitrogen determination of compounds having nitro group or azo group or nitrogen present in rings as the nitrogen of these compounds can not be converted to $\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}$ under the condition of this method.