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Solutions: Radioactivity Questions

Q7.

(a) Sketch a graph to show how the number of neutrons, N, varies with the number of protons, Z, for stable nuclei over the range Z = 0 to Z = 80. Draw a scale on the N axis.

straight line between (Z = 0, N = 0) to (Z = 20, N = 20) curving upwards to Z = 80; N = 110 –130

(2 marks)

(b) On the same graph, enclosing each region by a line, indicate the region in which nuclides are likely to decay, by

(i) emission, labelling the region A,

A = any region below the line of stability but N > 80 and Z > 60

(ii) emission, labelling the region B,

B = any region above and close to the line of stability

(iii) emission, labelling the region C.

C = any region below and close to the line of stability

(3 marks)

(c) Complete the table.

mode of decay

change in proton number Z

change in neutron number N

emission

–2

-2

 emission

+1

-1

 emission

-1

+1

e- capture

-1

+1

p emission

-1

0

n emission

0

-1

lose one mark for each row in error

(3 marks)

(8 Total Marks)