Polonium-211 (
) decays by alpha emission to form a stable isotope of lead (Pb).
Complete the equation for this decay.
The variation with time 
of the number of unstable nuclei 
in a sample of polonium-211 is shown in the graph below.
At time 
, the sample contains only polonium-211.
Use the graph above to determine the decay constant 
of polonium-211. Give a unit with your answer.
Use your answer in (b)(i) to calculate the activity at time of the sample of polonium-211.
Each decay releases an alpha particle with energy 
.
Calculate, in 
, the total amount of energy given to alpha particles that are emitted between time 
and time 
.
Suggest why the total amount of energy released by the decay process between time and time is greater than your answer in (c)(i).
.
.
.
