Which of the following is true about radioactive decay? October 4, 2022 by 8i9x6 Once a nucleus begins to decay it is destroyed. A helium atom was the first particle identified as a product of radioactive decay. Gamma decay depends on chemical reactions. Alpha decay results in one less neutron and one more proton. After beta decay, the number of protons in a nucleus is unchanged. See Answer A helium atom was the first particle identified as a product of radioactive decay.