Radioactivity

(a) A grazing pasture was polluted with radioactive waste from a nuclear reactor. A research carried out a study on the radioactive content in the milk collected from the cows in that area. He discovered the radioactive content in every liter of the milk was 1600 counts per minute.

The result of the study are shown in table below.

(b) On the graph paper below, draw a graph of radioactivity against time.

(i) Using the graph in (a)(i), determine the half-life of the radioactive material in the milk. Show on the graph how you determined the half-life.




(ii) Milk is safe to drink if the radioactivity in every liter of the milk is not more than 50 counts per minute.
using the half-life in (a)(ii), calculate the time when the milk from this area becomes safe to drink.








(b) In a nuclear reactor, radium-226 decays to become radon-222 by releasing one alpha article. This reaction experiences a mass defect.

(i) The number 226 for radium is called its ............... number


(ii) Complete the equation of the reaction by writing the appropriate number in the boxes provided.

(iii) The nuclear reaction of one nucleus of radium-226 experiences a mass defect

of 8.6818 X 10^-30 kg.

Calculate the energy released in the nuclear reaction.

The velocity of light is 3 x 10^-8ms^-1.

Answer 

Half-life = 7 days

time taken = 5  x  half-life

 = 5 x 7 days

= 35 days

nucleon number

E = mc²

 (8.6818 X 10^-30 kg)(3 x 10^-8ms^-1)²

7.81 X 10^-13 J