Answer :

To determine the parent nuclide of an unstable isotope that decays to produce silicon-31 and a beta particle, we need to consider the process of beta decay. In beta decay, a neutron within the nucleus is converted into a proton, an electron (beta particle), and an antineutrino. 1. Start with silicon-31 (Si-31), which is the product of the decay. 2. Identify the element that has one less proton than silicon-31, which would be phosphorus-31 (P-31). Phosphorus-31 has one less proton than silicon-31. 3. Determine the parent nuclide by looking for an isotope of phosphorus that undergoes beta decay to produce silicon-31. 4. The parent nuclide in this case is phosphorus-31 (P-31) because it undergoes beta decay by converting a neutron into a proton, resulting in the formation of silicon-31 and a beta particle. Therefore, the parent nuclide that decays to produce silicon-31 and a beta particle is phosphorus-31 (P-31).