Topic Menu

Cyber-chess a chess instruction site

GCSE Questions: Radioactivity

Q10.

Americium-241 is an isotope of americium.

 

(a) Which of the isotopes given in the table belowis not an isotope of americium?

Give a reason for your answer. [2 marks]

Isotopes are 'different physical versions' of the same element - they therefore have the same number of protons in the nucleus - but different number of neutrons.

Isotope B is not americium - to be americium it would need to have 95 protons in the nucleus and therefore an atomic number of 95.

Isotope
Mass number
Atomic number
A
243
95
B
243
94
C
242
95

 

(b) The graph below shows how the number of americium-241 nuclei in a sample changes with time.

Calculate the half-life of americium-241

440 Years

for showing how you used the graph - lines drawn on it - values read off the axes.

[2 marks]

(Total 4 marks)