Multiple Choice
What is the atomic number of the element with the symbol Ca?
78
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2. Atoms & Elements
Periodic Table: Element Symbols
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Which element has 78 protons in its nucleus?
A
Platinum (Pt)
B
Lead (Pb)
C
Iridium (Ir)
D
Gold (Au)
Verified step by step guidance1
Recall that the number of protons in the nucleus of an atom defines the atomic number of the element.
Identify the atomic number corresponding to 78 protons, since the atomic number equals the number of protons.
Use the periodic table to find the element with atomic number 78.
Check the element symbols and names for atomic number 78; this element is Platinum (Pt).
Confirm that none of the other options (Lead, Iridium, Gold) have atomic number 78 to ensure the correct choice.
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