Question

question 16 (1 point)
when an alpha particle is emitted from an unstable nucleus, the atomic mass number
of the nucleus
increases by 2.
decreases by 2.
increases by 4.
decreases by 4.

Explanation:

An alpha particle consists of 2 protons and 2 neutrons, so its mass number is 4 (since mass number = number of protons + number of neutrons). When a nucleus emits an alpha particle, it loses 4 mass units (2 protons + 2 neutrons). So the atomic mass number of the original nucleus decreases by 4.

Answer:

decreases by 4.