Which element is formed when a beta particle is emitted from sodium-24?

When a beta particle is emitted from sodium-24, the process involves the transformation of a neutron into a proton within the sodium nucleus. This transformation increases the atomic number of the element while keeping the mass number the same.

Sodium-24 has an atomic number of 11 (as sodium is the 11th element in the periodic table). When it undergoes beta decay, it converts one of its neutrons into a proton, changing its atomic number from 11 to 12, which corresponds to the element magnesium. The mass number remains 24 since the total number of nucleons (protons + neutrons) does not change during this process. Thus, the resulting element after the emission of the beta particle is magnesium-24, represented by the notation Mg-24.

This understanding clearly identifies magnesium (Mg) as the correct element formed, confirming the choice given in the response.