Multiple Choice
The mass number of an isotope is
21. Nuclear Chemistry
Intro to Radioactivity
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What is the parent nuclide of the nuclear reaction that produces the daughter nuclide Hg-208 when undergoing beta decay?
A
Au-208
B
Tl-208
C
Hg-209
D
Pt-204
E
Au-204
Verified step by step guidance1
Understand that in beta decay, a neutron in the nucleus is transformed into a proton, and a beta particle (an electron) is emitted. This increases the atomic number by 1 while the mass number remains unchanged.
Identify the daughter nuclide given in the problem: Hg-208. This means the atomic number of mercury (Hg) is 80, and the mass number is 208.
Since beta decay increases the atomic number by 1, the parent nuclide must have an atomic number that is one less than that of mercury. Therefore, the parent nuclide should have an atomic number of 79.
Look at the periodic table to find the element with atomic number 79, which is gold (Au).
Combine the element symbol for gold (Au) with the mass number 208 to identify the parent nuclide as Au-208.
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