Multiple Choice
How many neutrons are present in an atom of tin-120 (Sn-120)?
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2. Atoms & Elements
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Multiple Choice
An atom has an atomic number of 25 and a mass number of 55. How many neutrons are present in its nucleus?
A
25
B
80
C
55
D
30
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Verified step by step guidance1
Identify the atomic number (Z) and the mass number (A) from the problem. The atomic number is 25, and the mass number is 55.
Recall that the atomic number (Z) represents the number of protons in the nucleus of the atom.
Understand that the mass number (A) is the total number of protons and neutrons in the nucleus.
Use the formula to find the number of neutrons (N): \(N = A - Z\).
Substitute the given values into the formula: \(N = 55 - 25\) to find the number of neutrons.
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