Question detail
What is the mass number of an isotope with 10 protons and 12 neutrons?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
A simple model of the atom, symbols, relative atomic mass, electronic charge and isotopes
Question
- A. 10
- B. 12
- C. 22
- D. 2
Answer
22
Explanation
The mass number is the sum of protons and neutrons; therefore, 10 protons + 12 neutrons = 22.
Common mistake
Confusing Atomic Number and Mass Number
Students often confuse atomic number with mass number when using isotope notation.
Remember that atomic number refers to the number of protons, while mass number is the total of protons and neutrons. Use the notation correctly to distinguish between the two.
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