SAT Subject Physics Practice Question 198: Answer and Explanation
Identify the particle X resulting from the nuclear reaction shown above.
E. Alpha particle
Correct Answer: D
To balance the superscripts, we write 2 + 2 = 3 + A, and get A = 1. Now, to balance the subscripts, we write 1 + 1 = 2 + Z, so Z = 0. Therefore, the particle X has a mass number of 1 and a charge of 0; it’s a neutron.