Which of the following fertilizers has the highest nitrogen percentage?

Options

A. Ammonium sulphate
B. Urea
C. Calcium cyanamide
D. Ammonium nitrate

Answer

B

Explanation

Calculating the percentage of `N` in various compounds:
`% N = (m_(N))/(m_(comp.)) xx 100%`
Ammonium sulphate `[(NH_(4))_(2)SO_(4)] = (28)/(132) xx 100% = 21.2%`
Urea `[H_(2)NCONH_(2)] = (28)/(60) xx 100% = 46.6%`
Calcium cyanamide `(CaNCN) = (28)/(80) xx 100% = 35%`
Ammonium nitrate `(NH_(4)NO_(3)) = (28)/(80) xx 100% = 35%`
Thus, urea has the highest percentage of `N`.
Shortcut method:
Every compound has `2 N` atoms (i.e., same mass of `N`), thus compound with the lowest molecular mass (i.e., urea) will have the highest `N` percentage.