Question

The mass percentage of nitrogen in urea ($N{H}_{2}CON{H}_2$)is:

• A. $85$
• B. $46$
• C. $18$
• D. $28$

Answer 1

The correct option is B $46$

Molecular mass of urea ($N{H}_{2}CON{H}_2$) is
= 2$\times$ Atomic mass of N + 4 $\times$ (Atomic mass of H) + Atomic mass of C + Atomic mass of O = 60

Mass percentage of nitrogen = $\frac{\text{Mass of an element}}{\text{Mass of compound}}\times 100=46.67\%$