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Multiple Choice
How many neutrons are present in an atom of thorium-234?
A
234
B
90
C
144
D
146
Verified step by step guidance
1
Identify the atomic number (Z) of thorium, which is the number of protons in the nucleus. For thorium, Z = 90.
Recognize that the number 234 given with thorium (thorium-234) is the mass number (A), which represents the total number of protons and neutrons in the nucleus.
Use the relationship between mass number, protons, and neutrons: \(A = Z + N\), where \(N\) is the number of neutrons.
Rearrange the formula to solve for neutrons: \(N = A - Z\).
Substitute the known values into the equation: \(N = 234 - 90\), which will give the number of neutrons in thorium-234.