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Iodine-131 is used in hospitals - Edexcel - GCSE Physics - Question 4 - 2016 - Paper 1
Question 4
Iodine-131 is used in hospitals. The graph shows the decay of a sample of iodine-131. (i) Use the graph to find the half-life of iodine-131.
Worked Solution & Example Answer:Iodine-131 is used in hospitals - Edexcel - GCSE Physics - Question 4 - 2016 - Paper 1
Step 1
Use the graph to find the half-life of iodine-131.
Answer
To find the half-life from the graph, locate the mass of iodine-131 at the starting point, which is approximately 200 mg. The half-life is the time taken for the mass to reduce to half its initial value, which is 100 mg.
- Starting at 200 mg, follow the curve downwards to find where it intersects with the 100 mg line on the mass-axis.
- Read the corresponding time on the time-axis, which is approximately 8 days.
Thus, the half-life of iodine-131 is approximately 8 days.