Topic Menu

Cyber-chess a chess instruction site

A level: Radioactivity Questions

Q2.

(a)

(i) What is meant by the random nature of radioactive decay?

(ii) Explain what is meant by each of the following:

    • isotopes
    • radioactive half-life
    • radioactive decay constant

( 6 marks)

(b) The radioactive isotope of iodine 131I has a half-life of 8.04 days. Calculate

(i) the decay constant of 131I,

(ii) the number of atoms of 131I necessary to produce a sample with an activity of 5.0 × 104 disintegrations s–1 (Bq),

(iii) the time taken, in hours, for the activity of the same sample of 131I to fall from 5.4 × 104 disintegrations s–1 to 5.0 × 104 disintegrations s–1

(6 marks)

(Total 12 marks)