Respuesta :
Answer:
The parent isotope in the given elements is Radium 226.
Explanation:
The two elements given in the question are radioactive elements radon and Helium which are formed after an Alpha decay happens in the radium 226 to form Radon 222.
Radon has many isotopes out of which here radon 222 is formed which is a noble gas that is odourless colourless but Radioactive. Again in this reaction helium is formed which is again a noble gas and very light in weight.
