What fraction of a sample of Cs-137 will remain after 90.6 years?

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12. complete each of the following word equations for synthesis reactions. a. sodium + oxygen -> b. magnesium + fluorine -> 13. complete and balance the equations for the decomposition reactions. a. hgo -> [with the triangle heat symbol above the arrow] b. h2o(l) -> [with "electricity" written above the arrow]

Use examples from the article to explain one positive and one negative effect that chemistry has had on society.