Question 17N.3.hl.TZ0.21

${}_{71}^{177}\text{Lu}\to {}_{71}^{177}\text{Hf}+{}_{-1}^0\text{e}$ «+ $\nu$»

Hf

correct A and Z AND beta product

Accept “β/ β^–/e/e^–” for “${}_{-1}^0\text{e}$”.

Accept “¹⁷⁷Lu → ¹⁷⁷Hf + e^– «+ $\nu$»”.

number of half-lives = $\frac{t}{t_{{}^{\frac{1}{2}}}}$ = 2.08

OR

$\frac{N\left(t\right)}{N_0}={0.5}^{\frac{14.0}{6.73}}$

OR

$\lambda =$ «$\frac{\text{ln}2}{t_{{}^{\frac{1}{2}}}}=\frac{\text{ln}2}{6.73}=$» 0.103 «day^–1»

OR

$\frac{N\left(t\right)}{N_0}=e^{-0.103\times 14.0}$

23.6 «%»

Award [2] for correct final answer.

Any two of:

emits weak ionising radiation

OR

low activity/radioactivity

can be stored until material becomes inactive AND then disposed with normal waste

«isotopes» have short lives

OR

exist for a short period of time

Award [1 max] for “low-level waste/LLW”.

[Max 2 Marks]