Which reaction correctly describes the preparation of pure dinitrogen in the laboratory using $\text{Ba}({\text{N}}_3{)}_2$?

Solution

1. Pure dinitrogen is obtained by the thermal decomposition of metal azides.
2. The reaction is $\text{Ba}({\text{N}}_3{)}_2\stackrel{\Delta }{\to }\text{Ba}+3{\text{N}}_2$.
3. Other methods like ammonium dichromate decomposition produce impurities.
4. Hence the answer is (B).