객관식
What is the mass number of an atom with 5 protons and 7 neutrons?
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2. Atoms & Elements
Atomic Mass
Multiple Choice
What is the atomic number for potassium?
A
19
B
21
C
20
D
18
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검증된 단계별 안내1
Understand that the atomic number of an element is the number of protons in the nucleus of an atom of that element.
Recall that each element on the periodic table has a unique atomic number, which is usually found above the element symbol.
Locate potassium on the periodic table. Potassium is represented by the symbol 'K'.
Identify the atomic number of potassium by looking at the number above the symbol 'K' on the periodic table.
Recognize that the atomic number of potassium is 19, which means it has 19 protons in its nucleus.
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