Answer:
[tex]^{218}_{85}At\rightarrow ^{214}_{83}Bi+^{4}_{2}He[/tex]
Explanation:
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In this case, since the radioactive reaction for the alpha emission of astatine-218 to bismith-214 involve the release of a helium atom as shown below:
[tex]^{218}_{85}At\rightarrow ^{214}_{83}Bi+^{4}_{2}He[/tex]
Whereas the atomic number decreases by 2 and the mass number by 4 in agreement to the release of the Helium atom.
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