Question

1. Isotopes with an unstable nucleus
are radioactive ***
are extremely rare
change into radioisotopes
are only found in elements with many protons

2. When Lr-256 undergoes alpha decay, it becomes
Es-252
Md-252 *** [Explanation: Lr 256 - 4 = 252, Lr 103 - 2 = 101 (Md)]
Lr-252
Md-254

3. A high-powered photon is a(n)
alpha particle
gamma particle ***
beta particle
positron

4. In a nuclear equation, a neutron can spontaneously change into a(n)
alpha particle
positron and electron
beta particle and proton ***
gamma particle

5. A radioisotope emits a beta particle. That means a(n)
neutron changed into a proton***
proton changed into a neutron
proton changed into an electron
electron got lost

Answer 1

Those look OK to me.