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Question 19N.3.hl.TZ0.c

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Date November 2019 Marks available [Maximum mark: 2] Reference code 19N.3.hl.TZ0.c
Level hl Paper 3 Time zone TZ0
Command term Calculate Question number c Adapted from N/A
c.
[Maximum mark: 2]
19N.3.hl.TZ0.c

Nuclear medicine uses small amounts of radioisotopes to diagnose and treat some diseases.

25.0 μg of iodine-131, with a half-life of 8.00 days, was left to decay.

Calculate the mass of iodine-131, in μg, remaining after 32.0 days. Use section 1 of the data booklet.

[2]

Markscheme

ALTERNATIVE 1
4 half-lives ✔
1.56 «μg of iodine-131 remain» ✔

 

ALTERNATIVE 2
m = 25.0 1232.08.00 ✔
1.56 «μg of iodine-131 remain» ✔

 

ALTERNATIVE 3
λ = « ln 28.00 » = 8.66 × 10−2 «day−1» ✔
m = «  25.0   e − 8.66 × 10 − 2 × 32.0 = » 1.56 «μg of iodine-131 remain» ✔

 

Award [2] for correct final answer.

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