Answer:
67
Explanation:
- The atomic number (Z) of an atom is equal to the number of protons in the nucleus
- The mass number (A) of an atom is equal to the sum of protons and neutrons in the nucleus
Therefore, calling p the number of protons and n the number of neutrons, for element X we have:
Z = p = 23
A = p + n = 90
Substituting p=23 into the second equation, we find the number of neutrons:
n = 90 - p = 90 - 23 = 67
Atomic number=Proton count
Atomic mass=Proton count+ neutron count
Neuton Count=Atomic mass-Proton count
Proton count=Atomic number=27
Mass number=74
Neuton count= 74-27=47
