Question

85ra²²⁶
experiences three A-decay find
the number of heutrons in dangter
element​

Answer 1

When an alpha decay takes place, an alpha particle or a doubly ionized Helium atom is released ( He⁺²)  .

So, the atomic number decreases by two (2 protons are lost) and the mass number decreases by four ( 2 protons and 2 neutrons are lost) .

So, after three successive alpha decays, the atomic number reduces by

3 X 2=6 and the mass number decreases by 3 X 4=12, so the new element formed when ₈₅Ra²²⁶ undergoes 4 consecutive alpha decays will have atomic number 79 and mass number of 214. The number of neutrons will be: 214-79=135 neutrons .

This atom will still be radioactive as the number of neutrons (135) is still much greater than the number of protons (79) .