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Multiple Choice
How many neutrons are in an atom of magnesium-25 ()? (Assume magnesium has atomic number .)
A
B
C
D
Verified step by step guidance
1
Identify the atomic number of magnesium, which is given as 12. The atomic number represents the number of protons in the nucleus of the atom.
Recognize that the superscript number in magnesium-25 (the 25 in \(^{25}Mg\)) is the mass number, which is the total number of protons and neutrons in the nucleus.
Use the relationship between mass number (A), atomic number (Z), and number of neutrons (N): \( A = Z + N \).
Rearrange the formula to solve for the number of neutrons: \( N = A - Z \).
Substitute the known values into the equation: \( N = 25 - 12 \), which will give the number of neutrons in magnesium-25.