Question

The half-life of a decaying radioactive isotope is the time it takes for half of the original mass of the isotope to decay. If the mass (in grams) of a particular radioactive sample is given by M(t)=30e^(-0. 05t) where t is in years, what is the half-life of that isotope?

Round your answer to 2 decimal places. Do not include units

Answer 1

Step-by-step explanation:

The half-life of 20F is 11.0 s. If a sample initially contains 5.00 g of 20F, how much 20F remains after 44.0 s?

Solution

If we compare the time that has passed to the isotope’s half-life, we note that 44.0 s is exactly 4 half-lives, so we can use Equation ???

with n=4

. Substituting and solving results in the following:

amountremaining=5.00g×(12)4=5.00g×116=0.313g

Less than one-third of a gram of 20F remains.