the half life of I -137 is 8.07 days. if 24 grams are left after 40.35 days, how many grams were in the original sample?

768g

Explanation:

We can use to formula . Here, N(A) is the final amount. N0 is the initial amount. t is the time elapsed, and is the half life. Plugging in, we get the answer above.

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"

particle   p is an electron and particle q is a neutron