What does the ? represent in the bombardment equation of nitrogen-14? N + ? → C + H

Question

What does the ? represent in the bombardment equation of nitrogen-14?  N + ? →  C +  H

Quizplus · Accepted Answer

The bombardment of nitrogen-14 results in carbon-14 and hydrogen. The mass number of nitrogen-14 is 14, while the sum of mass numbers of carbon-14 and hydrogen is also 14. This means that no particles are gained or lost during the reaction. Therefore, the missing particle must be a neutron (no charge, and a mass number of 1 is negligible compared to the masses of nitrogen and carbon).

What Does the ? Represent in the Bombardment Equation of Nitrogen-14