Multiple Choice
How many neutrons are present in an atom of thorium-234?
2. Atoms & Elements
Isotopes
Multiple Choice
Which of the following isotopes has 45 neutrons?
A
Titanium-45 (Ti, atomic number 22)
B
Scandium-66 (Sc, atomic number 21)
C
Vanadium-68 (V, atomic number 23)
D
Calcium-45 (Ca, atomic number 20)
Verified step by step guidance1
Recall that the number of neutrons in an isotope is given by the difference between the mass number (A) and the atomic number (Z): \(\text{Number of neutrons} = A - Z\).
Identify the mass number (the number after the element name) and the atomic number (given for each element) for each isotope option.
Calculate the number of neutrons for Titanium-45: \(45 - 22\).
Calculate the number of neutrons for Scandium-66: \(66 - 21\).
Calculate the number of neutrons for Vanadium-68: \(68 - 23\), and for Calcium-45: \(45 - 20\), then compare all results to find which isotope has exactly 45 neutrons.
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