By what (single step) process does radon-226 decay to francium-236?

Question

By what (single step) process does radon-226 decay to francium-236?

a.neutron capture
b.β particle emission
c.α particle emission
d.positron emission
e.electron capture

Answer 1

Radon 226 _could_ decay into Francium **226** by beta emission, which would change a neutron into a proton, thus raising the atomic number by 1 while leaving the atomic mass essentially unchanged. So the answer to the question would be B.

In real life, this does not happen. Radon 226 decays by alpha emission into Polonium 222.

Answer 2

Radon 226 doesn't decay into heavier products. In general radioactive elements decay into lighter elements, eventually all of them turning into lead. That being said, radon 226 will decay into radon 222 single step through alpha particle emission. Also, there is no isotope of Fr that weighs 236. The range of isotope masses goes from 199 to 232.

The full decay chain it belongs to, from U238 to Pb 206 is:

238U (4.5 x 109 yr), 234Th (24.1 days), 234Pa (1.18 min), 234U (2.457 x 105 yr), 230Th (75,000 yr), 226Ra (1,600 yr), 222Rn (3.82 days), 218Po (3.1 min), 214Pb (26.8 min), 214Bi (19.7 min), 214Po (164 µs), 210Pb (22.3 yr), 210Bi (5.01 days), 210Po (138 days), 206Pb (stable).