A radioactive isotope phosphorous-32 has an initial activity 10 μCi and has half life of 14 days. What is the activity of the source after 42 days?

1.25 μCi 2.5 μCi 5 μCi 0.625 μCi

1.25 μCi

The correct answer is Option (1) → 1.25 μCi