When Th undergoes alpha decay,what is the atomic mass of the element that is produced?

Question

When  Th undergoes alpha decay,what is the atomic mass of the element that is produced?

Quizplus · Accepted Answer

In alpha decay, an alpha particle (a helium nucleus) is emitted from the nucleus. This means that the atomic number decreases by 2 and the mass number decreases by 4. 
Starting with 11ea71d6_78d7_a650_91e5_a3195765b4cf_TB6110_11, we know that the atomic number (the subscript) is 110 and the mass number (the superscript) is 271. 
After alpha decay, the new atomic number will be 110-2 = 108 and the new mass number will be 271-4 = 267. 
Therefore, the element produced will have an atomic mass of 228, which corresponds to choice B.

When Th Undergoes Alpha Decay,what Is the Atomic Mass