Question

What is the half life of a radioisotope if 25.0 grams of anoriginal 200.-gram sample of the isotope remainsunchanged after 11.46 days?3) 11.46 d1) 2.87 d4) 34.38 d2) 3.82 d

Answer 1

Half-life is the amount of time, in days or years( most common) a certain substance disintegrate half of it's content.
We are given the initial (Ao) and final (A) amount of the substance. The time passed (T) is also given and we are asked to find the half-life (t). We use the equation below:

A=Aoe^(-ln2/t)T
25=200e^(-ln2/t)(11.46)
Solve for t
Answer: 3.82 days