Final answer:
The number of N atoms in the reactants in the chemical equation 2 NaN₃ (s) → 3 N₂(g) + 2 Na (s) is 9.
Step-by-step explanation:
The chemical equation is 2 NaN₃ (s) → 3 N₂(g) + 2 Na (s).
To identify the number of N atoms in the reactants, we look at the coefficients of the balanced equation. We can see that there are 3 N atoms on the product side (3 N₂), so there must be 3 N atoms on the reactant side as well. Therefore, the correct answer is option d) 9.