If the half-life of uranium-238 is about 4.51 x 10^9 years then what is its decay constant in units of atoms per year?
Choose one answer.
a. 9.72x10^-8
b. 2,55
c. 7.89 x 10^4
d. none of the other answers are correct
e. 9.72x10^-10

I got ln2/4.51x10^9 but the answer is b) 9.72x10^-10

Question

If the half-life of uranium-238 is about 4.51 x 10^9 years then what is its decay constant in units of atoms per year?
Choose one answer.
	 a. 9.72x10^-8	
	 b. 2,55	
	 c. 7.89 x 10^4	
	 d. none of the other answers are correct	
	 e. 9.72x10^-10

I got ln2/4.51x10^9 but the answer is b) 9.72x10^-10

jfraser · Answer

The correct answer is D. http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/halfli2.html#c4

jfraser · Answer

Your setup is correct. Since $$T{_1}{_/}{_2} = \ln2/\lambda$$ then $$\lambda = \ln2/T{_1}{_/}{_2}$$.

Plug and chug, and you should get an answer of 1.54x10^(-10).

anonymous · Answer

0.693/ k=half life.