DP Chemistry (last assessment 2024)

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Question 23M.3.HL.TZ1.20

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Date May 2023 Marks available [Maximum mark: 6] Reference code 23M.3.HL.TZ1.20
Level HL Paper 3 Time zone TZ1
Command term Describe, Determine, Suggest Question number 20 Adapted from N/A
20.
[Maximum mark: 6]
23M.3.HL.TZ1.20

Two radiation treatments for cancer are Targeted Alpha Therapy, TAT, and Boron Neutron Capture Therapy, BNCT.

(a)

Describe which cancers are treated by TAT and BNCT and the particles used in each treatment.

 

TAT: 

 

 


BNCT:

 

 

 

[2]

Markscheme

TAT:
spread to multiple sites AND alpha particles
OR
«cancers of the» blood/leukaemia AND alpha particles ✓

BNCT:
head/neck/brain «cancers» AND neutrons ✓

 

Award [1] for 2 correct cancers or 2 correct particles.

(b)

Suggest two reasons why technetium-99m is the most commonly used radioisotope in nuclear medicine.

[2]

Markscheme

Any two of:
gamma radiation AND easily traced ✓
weak/low-energy/low-frequency «gamma» radiation «low risk to patient» ✓
short half-life «low risk to patient» ✓
binds to range of biologically-active substances ✓
«gamma-radiation of approximately» same frequency as X-rays «so can be detected using existing X-ray equipment» ✓
easily obtained ✓

 

Accept non-ionising radiation.

(c)

A freshly prepared solution for radiodiagnostics contains 1.0 × 10−7 mol dm−3 of technetium-99m. Determine the concentration, in mol dm−3, of technetium-99m remaining in the solution 22.00 hours later. Use section 1 of the data booklet.

Half-life of technetium-99m = 6.01 h

[2]

Markscheme

«Nt = N0(0.5)t/t1/2 =» 1.0 × 10−7 mol dm−3 × (0.5)22.00/6.01 ✓
«Nt =» 7.9 × 10−9 «mol dm−3» ✓

 

Award [2] for correct final answer.