Which statement correctly describes positron decay?

• A. Proton transforms to a neutron and emits a positron
• B. Mass of a positron is much larger than an electron
• C. Involves emission of an alpha particle
• D. Decreases binding energy

Answer: (A)

Positron decay is a form of beta-plus decay: a proton inside the nucleus is converted into a neutron, and a positron is emitted along with a neutrino. This changes the element to have one less proton (atomic number down by 1) while leaving the mass number the same.

The statement that proton transforms to neutron and emits a positron captures the essential mechanism, so it best describes positron decay. A positron has the same mass as an electron, so the claim that its mass is much larger is false. Alpha particles are involved in alpha decay, not positron emission, so that option isn’t correct. And binding energy isn’t the defining feature of positron decay—the process is governed by the conversion of a proton to a neutron with the associated emission of a positron (and a neutrino), depending on the energy balance of the nucleus.