Compare nitrogen mass percentage in each fertilizer

Steps:

• Calculate molar mass (MM) for each: A. NH₄Cl = 53.5 g/mol; B. NH₄NO₃ = 80 g/mol; C. (NH₄)₂SO₄ = 132 g/mol; D. KNO₃ = 101 g/mol.
• Find nitrogen mass per formula: A. 14 g; B. 28 g; C. 28 g; D. 14 g.
• Compute %N = (N mass / MM) × 100: A. 26%; B. 35%; C. 21%; D. 14%.
• Mass of N in 50 kg = (%N / 100) × 50 kg; B yields highest at 17.5 kg.

Why B is correct:

• NH₄NO₃ contains two N atoms (28 g) in a relatively low MM (80 g/mol), giving the highest %N by mass per the formula for elemental composition.

Why the others are wrong:

• A: Single N atom with heavy Cl reduces %N to 26%.
• C: Two N atoms but heavy SO₄ group lowers %N to 21%.
• D: Single N atom with heavy K yields lowest %N at 14%.

Final answer: B