Answer:
12 days = Half-life
Explanation:
The radioactive decay for an isotope A follows the equation:
Ln[A] = -kt + Ln[A]₀
Where [A] is amount of A after time t, k is decay constant and [A]₀ is initial amount of the isotope.
Replacing:
Ln[A] = -kt + Ln[A]₀
Ln[0.015g] = -k*5days + Ln[0.020]
-0.2877 = -k*5days
0.0575days⁻¹ = k
And we can obtain Half-Life from decay constant as follows:
Ln 2 / k = Half-life
Ln 2 / 0.0575days⁻¹ = Half-Life
12 days = Half-life
