a) Use information about the decay series of uranium-238 to write balanced decay equations to represent the decay for thorium-234 ii) radium-226 iii) lead-214 (metastable) b) Plot a graph of the activity against time for a sample of protactinium-234. Use the graph to find the half-life of napa. c) The graph below shows the relationship between activity and the number of atoms in a sample of protactinium-234. Analyse the graph to find out whether it is consistent with the value of the half-life calculated in part (b). Number of atoms / x 106 d) The decay series of uranium-238 includes 3 different isotopes of polonium. Which of these isotopes you would expect to find with the greatest abundance in a sample of pitchblende? Explain your answer.