Answer: a) [tex]\frac{28gN}{80gNH_4NO_ 3}\times 100\%[/tex]
Explanation: Mass percentage is defined as the ratio of the mass of the particular element to the total mass of the substance multiplied by 100.
[tex]{\text{mass percentage}=\frac{\text{mass of the element}}{\text{Total mass}}\times {100}[/tex]
mass of nitrogen[2 atoms of N] = 28 g
Total mass of [tex]NH_4NO_ 3=2\times {\text {Mass of nitrogen}}+4\times {\text {mass of hydrogen}}+3\times {\text {mass of oxygen}}[/tex]
[tex]=2\times 14+4\times 1 +3\times 16=80 g[/tex]
[tex]{\text{mass percentage}=\frac{28}{80}\times {100}\%[/tex]
