Answer: 8
EXPLANATION:
atomic number = No. of protons
mass number or atomic mass = no. of protons + no. of neutrons
For oxygen atom, we know its atomic number is 8. So, no. of protons is 8 and we are given the atomic mass is 16.
use the equation above,
16 = 8 + no. of neutrons
no. of neutrons = 16 - 8 = 8.
