A Test Tube of an Isotope Having a Decay Constant $0.765 \times 10 ^ { - 6 } \mathrm {~s} ^ { - 1 }$

Short Answer

A test tube of an isotope having a decay constant of $0.765 \times 10 ^ { - 6 } \mathrm {~s} ^ { - 1 }$ contains $3.0 \times 10 ^ { 17 }$ nuclei of this isotope.
(a) What is the half-life of this isotope?
(b) What is the initial activity (in Bq) of the isotope?
(c) What is the activity of the isotope after 12 days?