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<h2>HL Paper 3</h2><div class="specification">
<p><span style="background-color: #ffffff;">Nuclear medicine uses small amounts of radioisotopes to diagnose and treat some diseases.</span></p>
</div>
<div class="question" style="padding-left: 20px; padding-right: 20px;">
<p><span style="background-color: #ffffff;">State <strong>two</strong> common side effects of radiotherapy.</span></p>
<div class="marks">[1]</div>
<div class="question_part_label">a.</div>
</div>
<div class="question" style="padding-left: 20px; padding-right: 20px;">
<p><span style="background-color: #ffffff;">Explain why technetium-99m is the most common radioisotope used in nuclear medicine.</span></p>
<div class="marks">[2]</div>
<div class="question_part_label">b.</div>
</div>
<div class="question" style="padding-left: 20px; padding-right: 20px;">
<p><span style="background-color: #ffffff;">25.0 μg of iodine-131, with a half-life of 8.00 days, was left to decay.</span></p>
<p><span style="background-color: #ffffff;">Calculate the mass of iodine-131, in μg, remaining after 32.0 days. Use section 1 of the data booklet.</span></p>
<div class="marks">[2]</div>
<div class="question_part_label">c.</div>
</div>
<h2 style="margin-top: 1em">Markscheme</h2>
<div class="question" style="padding-left: 20px;">
<p><span style="background-color: #ffffff;"><em>Any two of:</em><br>hair loss<br>fatigue<br>nausea<br>sterility<br>skin reaction<br>diarrhoea<br>vomiting<br>damage to lymph system<br>urinary/bladder changes<br>anxiety/emotional problems<br>joint/muscular stiffness<br>loss of appetite<br>sore/dry mouth<br>loss of weight<br><span style="text-decoration: underline;">secondary</span> cancer ✔</span></p>
<div class="question_part_label">a.</div>
</div>
<div class="question" style="padding-left: 20px;">
<p><span style="background-color: #ffffff;"><em>Any two of:</em><br>half-life is 6 hours/long enough for a scan to occur<br><em><strong>OR</strong></em><br>half-life short enough not to remain in body ✔<br><em>NOTE: Accept “short half-life so patient is not exposed to lots of ionizing radiation”.</em><br></span></p>
<p><span style="background-color: #ffffff;">decay releases «low energy» gamma rays<br><em><strong>OR</strong></em><br>gamma rays less likely to be absorbed by cells ✔</span></p>
<p><span style="background-color: #ffffff;">can form several «coordination» complexes ✔<br><em>NOTE: Accept "can exist in many oxidation states «so can form multiple complexes»" <strong>OR</strong> "chemically versatile «so can act as a tracer by bonding to several bioactive compounds»”.</em><br></span></p>
<p><span style="background-color: #ffffff;">«low-energy» radiation/gamma-rays can be detected by common X-ray equipment ✔</span></p>
<div class="question_part_label">b.</div>
</div>
<div class="question" style="padding-left: 20px;">
<p><span style="background-color: #ffffff;"><em><strong>ALTERNATIVE 1</strong></em><br>4 half-lives ✔<br>1.56 «μg of iodine-131 remain» ✔</span></p>
<p> </p>
<p><span style="background-color: #ffffff;"><em><strong>ALTERNATIVE 2</strong></em><br><em>m</em> = 25.0 <span class="mjpage"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\left( {\frac{1}{2}} \right)^{\frac{{32.0}}{{8.00}}}}"><msup><mfenced><mfrac><mn>1</mn><mn>2</mn></mfrac></mfenced><mfrac><mn>32.0</mn><mn>8.00</mn></mfrac></msup></math></span> ✔<br>1.56 «μg of iodine-131 remain» ✔</span></p>
<p> </p>
<p><span style="background-color: #ffffff;"><em><strong>ALTERNATIVE 3</strong></em><br><em>λ</em> = « <span class="mjpage"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="\frac{{\ln 2}}{{8.00}}"><mfrac><mrow><mi>ln</mi><mo> </mo><mn>2</mn></mrow><mn>8.00</mn></mfrac></math></span> » = 8.66 × 10<sup>−2</sup> «da</span>y<sup>−1</sup><span style="background-color: #ffffff;">» ✔<br><em>m</em> = « <span class="mjpage"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="25.0{\text{ }}{{\text{e}}^{ - 8.66 \times {{10}^{ - 2}} \times 32.0}} = "> <mn>25.0</mn> <mrow> <mtext> </mtext> </mrow> <mrow> <msup> <mrow> <mtext>e</mtext> </mrow> <mrow> <mo>−</mo> <mn>8.66</mn> <mo>×</mo> <mrow> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>−</mo> <mn>2</mn> </mrow> </msup> </mrow> <mo>×</mo> <mn>32.0</mn> </mrow> </msup> </mrow> <mo>=</mo> </math></span> » 1.56 «μg of iodine-131 remain» ✔</span></p>
<p> </p>
<p><em><span style="background-color: #ffffff;">Award <strong>[2]</strong> for correct final answer.</span></em></p>
<div class="question_part_label">c.</div>
</div>
<h2 style="margin-top: 1em">Examiners report</h2>
<div class="question" style="padding-left: 20px;">
[N/A]
<div class="question_part_label">a.</div>
</div>
<div class="question" style="padding-left: 20px;">
[N/A]
<div class="question_part_label">b.</div>
</div>
<div class="question" style="padding-left: 20px;">
[N/A]
<div class="question_part_label">c.</div>
</div>
<br><hr><br>