60.0 grams of Th-210 with a half life of 50,000 years is allowed to decay for 250,000 years. How much of the original quantity remains? In addition, Th-210 decays via beta emission. Write the equation for its transmutation.

Answer 1

The long way.
k = 0.693/t_1/2
ln(No/N) = kt
No = 60
N = solve for N.
k from above.
t = 250,000

First number is atomic number. Second number is mass number.
90Th210 ==> -1e0 + 91Pa210