Iodine-131 ($^{131}_{53}\text{I}$) is a radioactive isotope with decay constant $8.6 \times 10^{-2}\,\text{day}^{-1}$. The $\beta^{-}$ particles it emits have a maximum energy of $0.61\,\text{MeV}$.
(a(i))[2]
State the meaning of radioactive.
(a(ii))[2]
State the meaning of decay constant.
(b)[2]
Explain why the $\beta^{-}$ particles emitted have a spread of energies.
(c(i))[3]
A blood sample contains $1.2 \times 10^{-9}\,\text{g}$ of iodine-131. Find the activity of the iodine-131 in this blood sample.
(c(ii))[2]
Determine how long it takes for the iodine-131 activity to fall to $\frac{1}{50}$ of the activity found in (i).
Worked solution & mark scheme
This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Particles or EM radiation are emitted from an unstable nucleus” …