Rankers Physics

Nucleus: Practice Problem & Solution

The mass number of a nucleus is: (2003)
Always less than its atomic number
Always more than its atomic number
Sometimes equal to its atomic number
Sometimes less than and sometimes more than its atomic number

Solution Explained:

To solve this problem, we apply the core principles of Nucleus. Understanding the underlying formula is key to arriving at the correct answer below:

Mass number A is the sum of protons and neutrons, while atomic number Z is just the number of protons. For hydrogen ($^1H$), there are no neutrons, so A = Z. For all other stable nuclei, A > Z. Thus, it is sometimes equal.

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