Question

If a radioactive isotope has a half-life of 8 h, how many half lives would it take for an initial 10g sample to decay to 0.3125g

Answer 1

Answer: The answer is 1.6yrs

Explanation:

$0.3125= 10.(\frac{1}{2}) ^{\frac{8}{t(\frac{1}{2}) } } \\\\\\\frac{0.3125}{10} =( \frac{1}{2} )^{\frac{8}{t(\frac{1}{2})}} \\\\\frac{0.3125}{10} = 0.03125 \\\\\frac{8}{t(^{\frac{1}{2}} )} log_{o.5} (0.03125)\\\\\frac{8}{t^{\frac{1}{2} } } (5)=0\\\\t^{\frac{1}{2} } =\frac{8}{5} =1.6yrs$

I think this is the answer.