Question

The activity of a sample of a radioisotope at some time is 10.1 mCi and 0.36 h later it is 6.60 mCi. Determine the following:

(a)Decay constant (in s⁻¹)

(b) Half-life (in h)

(c) Nuclei in the sample when the activity was 10.1 mCi

(d) Activity (in mCi) of the sample 1.90 h after the time when it was 10.1 mCi

Answer 1

(1) Activitiy of sample;

activity after time t = 0.36 h = 0.36 x 3600 s = 1296 s

(A) find decay constant using following relation;

decay constant

(B) half life;

(C) since 1 Ci = 3.7 x 10^(10) Bq

therefore;

Nuclei in the sample;

(D) Activity (in mCi) of the sample 1.90 h after the time when it was 10.1 mCi;

Activity (in mCi) of the sample 1.90 h;