Question

The isotope 238U, which starts one of the natural radioactive series, decays first by alpha decay followed by two negative beta decays. At this point, what is the resulting isotope

Answer 1

Answer: The resulting isotope is $^{231}_{92}\textrm {U}$

Explanation:

Alpha Decay: In this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. The mass number is reduced by 4 units and atomic number is reduced by 2 units.

$^{235}_{92}\textrm{U} \rightarrow ^{231}_{90}\textrm {Th}+^{4}_{2}n$

Beta Decay : It is a type of decay process, in which a proton gets converted to neutron and an electron. This is also known as -decay. In this the mass number remains same but the atomic number is increased by 1.

$^{231}_{90}\textrm{Th}\rightarrow ^{231}_{92}\textrm {Th}+2^{0}_{-1}n$

The resulting isotope is $^{231}_{92}\textrm {U}$