Help!!!! chemistry ppl please.?

Question

whats the notation for the alpha particles emitted by radium in radium salts?

also,...

The radioisotopes carbon-14 & nitrogen-16 are present in a living organism, carbon-14 is commonly sed to date a once-living organism.
A wood sample is found to contain 1/8 as much c-14 as of present wood of a tree. what is the approximate age (in years) of the wood?

Answer 1

(subscript 2)(He)(superscript 4)

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Half of 1 is 1/2, half of 1/2 is 1/4, and half of 1/4 is 1/8. So the wood has lasted for three half-lives of carbon-14. If the half-life is 5500 years, then the wood is 16,500 years old.