The percentage of nitrogen in urea is about:

$\text{ Urea- }{\mathrm{NH}}_2-\mathrm{CO}-{\mathrm{NH}}_2$
$$\begin{gathered} \because 60\mathrm{gm}\text{ of urea contains }28\mathrm{gm}\text{ of nitrogen } \\ \therefore 100\mathrm{gm}\text{ of urea contains }\frac{28}{60}\times 100=46.66\text{. } \end{gathered}$$