Calculate mass percentage of nitrogen using molar masses Steps:

• Determine atomic masses: N=14, H=1, C=12, O=16, P=31, S=32.
• Compute molar mass for each: A=17, B=149, C=114, D=96.
• Find nitrogen mass: A=14 (1N), B=42 (3N), C=14 (1N), D=28 (2N).
• Calculate %N: A=(14/17)×100=82%, B=(42/149)×100=28%, C=(14/114)×100=12%, D=(28/96)×100=29%.

Why D is correct:

• (NH₄)₂CO₃ has the highest %N (29%) among solid ammonium salt fertilizers, as its formula has a higher N-to-total mass ratio per the percentage calculation.

Why the others are wrong:

• A: NH₃ has 82% N but is a gas, not a typical solid fertilizer.
• B: (NH₄)₃PO₄ has 28% N, lower due to heavier P and O atoms diluting N content.
• C: NH₄SO₄ has only 12% N from one NH₄ group versus two in D.

Final answer: D