Multiple Choice
Which of the following best describes the difference between atomic number and atomic mass?
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2. Atoms & Elements
Atomic Mass
Multiple Choice
What is the mass number for an atom of barium containing 56 protons and 78 neutrons?
A
134
B
78
C
122
D
56
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Verified step by step guidance1
Identify the number of protons and neutrons given in the problem. Here, the atom has 56 protons and 78 neutrons.
Recall that the mass number (A) of an atom is the total number of protons and neutrons in its nucleus.
Use the formula for mass number: \(A = Z + N\), where \(Z\) is the number of protons and \(N\) is the number of neutrons.
Substitute the given values into the formula: \(A = 56 + 78\).
Add the numbers to find the mass number, which represents the total nucleons in the atom.
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