Calculate the percentage by mass of nitrogen in calcium trioxonitrate (V), Ca(NO₃)₂. [Ca = 40, N = 14, O = 16]

Step 1: Write the chemical formula
The compound is calcium trioxonitrate (V), which is Ca(NO₃)₂.

Step 2: Calculate the molar mass

• Calcium (Ca) = 40
• Nitrogen (N) = 14 × 2 = 28
• Oxygen (O) = 16 × 6 = 96

Total molar mass = 40 + 28 + 96 = 164 g/mol

Step 3: Calculate the percentage by mass of nitrogen

\[ \text{Percentage of N} = \frac{\text{Mass of nitrogen}}{\text{Molar mass of compound}} \times 100 = \frac{28}{164} \times 100 \]

Now calculate: 28 ÷ 164 ≈ 0.1707 0.1707 × 100 = 17.1%

Correct Answer: 17.1%