Final answer:
Compared to the stable isotope ^31P, the radioactive isotope ^32P is more radioactive due to its higher neutron-to-proton ratio.
Step-by-step explanation:
Compared with ^31P , the radioactive isotope ^32P has an extra neutron, resulting in a neutron-to-proton ratio that is higher than the stable isotope. This higher neutron-to-proton ratio makes ^32P more likely to undergo radioactive decay. Therefore, ^32P is more radioactive than ^31P.