9. the largest source of radiation in most people's lives is
a. medical uses
c. industrial applications
b. natural background radiation d. nuclear weapons testing
10. a radioactive gas that enters many houses from the ground below
a. radium
b. radon
c. carbon-14
d. tritium

9 . The correct answer is B. Natural background radiation. Because the biggest source of natural background radiation is airborne radon, a radioactive gas that emanates from the ground.

10. The correct answer is B. Radon.

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a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.