Final answer:
The reaction 40/19K → 0/-1e + 40/20Ca demonstrates beta decay, where 40K, a rare isotope of potassium, emits an electron and transforms into 40Ca.
Step-by-step explanation:
The type of decay process demonstrated in the reaction 40/19K → 0/-1e + 40/20Ca is known as beta decay. In this process, an isotope of potassium, 40K, transforms into calcium, 40Ca, while emitting an electron (symbolized as 0/-1e, also known as a beta particle).
Beta decay is a common decay mode for radioactive isotopes and is a change that involves the conversion of a neutron into a proton within the nucleus, resulting in the emission of the electron.
40K is known to be a naturally occurring rare isotope of potassium. This isotope plays a role in our exposure to background radiation as it decays. During its beta decay, a neutron present in the potassium isotope converts into a proton, and as a part of this reaction, an electron is emitted. The atomic number thus increases by one, but the atomic mass remains unchanged, making calcium the product.
These types of nuclear reactions play a crucial role in various fields, including geological dating techniques where isotopes like carbon-14 and potassium-40 are used to determine the age of ancient objects and geological formations.