Answer:
1.25 g
Explanation:
Now we have to use the formula;
N/No = (1/2)^t/t1/2
N= mass of cesium-137 left after a time t (the unknown)
No= mass of cesium-137 present at the beginning = 5.0 g
t= time taken for 5.0 g of cesium-137 to decay =60 years
t1/2= half life of cesium-137= 30 years
Substituting values;
N/5= (1/2)^60/30
N/5= (1/2)^2
N/5= 1/4
4N= 5
N= 5/4
N= 1.25 g
Therefore, 1.25 g of cesium-137 will remain after 60 years.
