Question

What elements undergo positron decay?

Answer 1

Positron emission or beta plus decay (β+ decay) is a particular type of radioactive decay and a subtype of beta decay, in which a proton inside a radionuclide nucleus is converted into a neutron while releasing a positron and an electron neutrino (νe).[1] Positron emission is mediated by the weak force. The positron is a type of beta particle (β+), the other beta particle being the electron (β−) emitted from the β− decay of a nucleus.

Okay coming to the point

Isotopes which undergo this decay and thereby emit positrons `to`carbon-11
`to`potassium-40,
`to`nitrogen-13,
`to` oxygen-15,
`to`aluminium-26,
`to` sodium-22,
`to` fluorine-18,
`to` iodine-121.