Answer:
one beta particle
Step-by-step explanation:
Since the atomic number of 131_I_53 increases by one to 131_Xe_54, we have the release of a beta particle since only a beta particle can cause a change in atomic number without a change in mass number. Since a beta particle is one electron, ₋₁⁰e, our nuclear equation is
¹³¹I₅₃ → ¹³¹X₅₄ + ₋₁⁰e
The atomic and mass numbers on both sides are balanced
mass number 131 = 131 + 0 = 131
atomic number 53 = 54 - 1 = 53
Thus a beta particle is emitted