Based on reference table n what fraction of a radioactive 90sr sample would remain unchanged after 58.2 years?

Answer: 1/4.
Explanation: Strontium-90 is a radioactive nuclide of the chemical element strontium with a mass number of 90.
90Sr enters the environment mainly during nuclear explosions and emissions from nuclear power plants.
Prolonged radiation exposure to 90Sr affects bone tissue and bone marrow, which leads to the development of radiation sickness, tumors of hematopoietic tissue and bones.
The isotope strontium 90Sr has a half-life of 28.79 years. => 58.2 / 28.79 = 2 => For 28.79 years - 1/2, for the second 28.79 years half of 1/2, that is 1/4.

 

1.consider the following balanced equation and answer parts a through. show calculations for each part.  

3 ag(s) + 4 hno3(aq) → 3 agno3(aq) + no(g) + 2 h2o(l)  

a. calculate the number of moles of agno3 produced by the reaction of 3 moles of ag with excess hno3. if the number to the left of the compound represents the number of moles of the compound which are present, then 3 moles of ag react with 4 moles hno3 to produce 3 moles agno3 (aq).

 

so the answer to a would be 3 moles.

b. calculate the number of moles of agno3 produced by the reaction of 108 grams of ag with excess hno3.  

i'm not sure how to plug in the grams of silver into an equation using moles to find how many moles are produced.

c. calculate the number of grams of agno3 produced by the reaction of 108 grams of ag with excess hno3  

d. calculate the number of moles of no produced as a byproduct of the reaction of 108 grams of ag with excess hno3.  

e. calculate the number of grams of no produced as a byproduct starting with 108 grams of ag and excess hno3.  

explanation:

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