A Sample of a Radioactive Isotope Is Found to Have

Multiple Choice

A sample of a radioactive isotope is found to have lost 19.8% of its original activity after 8.59 days.What is the decay constant of this isotope?

A) 0.026 d−1
B) 0.188 d−1
C) 1.89 d−1
D) 0.021 d−1
E) 0.51 d−1