Question

What change occurs in the nucleus when an alpha particle is emitted?

a) The atomic number decreases by 2.
b) The atomic number increases by 2.
c) The mass number decreases by 4.
d) The mass number increases by 4.

Answer 1

When an alpha particle is emitted, the atomic number decreases by 2 and the mass number decreases by 4.

Step-by-step explanation:

b) Alpha particles have the symbol He. Emitting an alpha particle causes the atomic number to decrease by 2 and the mass number to decrease by 4. We are left with:

¹4Ce+¹4N

234 Th

238U→He+2907

This means that when an alpha particle is emitted, the atomic number decreases by 2 (option a), and the mass number decreases by 4 (option c).