객관식
How many neutrons are present in the nucleus of a sodium atom with a mass number of 23?
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2. Atoms & Elements
The Atom
Multiple Choice
How many protons are present in a neutral atom of scandium?
A
44
B
23
C
21
D
12
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검증된 단계별 안내1
Identify the element in question, which is scandium in this problem.
Recall that the number of protons in a neutral atom is equal to the atomic number of the element.
Look up the atomic number of scandium on the periodic table; the atomic number is the number of protons.
Note that the atomic number of scandium is 21, meaning a neutral scandium atom has 21 protons.
Confirm that the number of protons equals the number of electrons in a neutral atom, but the question only asks for protons.
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