(a)[2]
State what a β-particle is and state its charge.
(b)[2]
Use the graph to determine the half-life. Show your working on the graph.
(c(i))[2]
Calculate the count rate of the caesium-137 in the sample after 60 years.
(c(ii))[2]
Suggest why people are unwilling to live near the power station, even after it has shut down.