Multiple Choice
What is the mass number of an atom of potassium that has 20 neutrons?
2. Atoms & Elements
Isotopes
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How many protons are present in an atom of potassium-29?
A
29
B
18
C
19
D
20
Verified step by step guidance1
Identify the element in question, which is potassium. The chemical symbol for potassium is 'K'.
Locate potassium on the periodic table to find its atomic number. The atomic number of an element represents the number of protons in an atom of that element.
The atomic number of potassium (K) is 19. This means every atom of potassium has 19 protons.
The mass number given in the problem, 29, refers to the total number of protons and neutrons in the nucleus of the atom. However, the number of protons is determined solely by the atomic number.
Therefore, regardless of the mass number, the number of protons in an atom of potassium is 19, as indicated by its atomic number.
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