In the given nuclear reaction, one of the reactant is Boron-10, and the products are Nitrogen-13 and neutron. So, the sum of mass numbers of Nitrogen - 13 and neutron is 13 + 1 =14 and the sum of atomic numbers is 7 + 0 = 7 on the product side. On the reactant side the other reactant will have a mass number of 14 - 10 = 4 and an atomic number of 7-5 = 2. So, the other reactant will be alpha particle.
This nuclear reaction representing the bombarding of Boron-10 with the radioactive alpha particle to yield Nitrogen-13 and a neutron is:
[tex]^{10}_{5}B+^{4}_{2}He-->^{13}_{7}N+_{0}^{1} n[/tex]
