Answer:
26
Step-by-step explanation:
Given parameters:
Number of neutrons = 14
Unknown:
Mass number = ?
Solution:
The mass number of an atom is the sum of protons and neutrons in the atom.
mass number = number of protons + number of neutrons
Since the atom here is magnesium, number of protons is 12
Mass number = 14 + 12 = 26