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Question 19M.3.hl.TZ2.26b

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.3.hl.TZ2.26b
Level hl Paper 3 Time zone TZ2
Command term Calculate Question number b Adapted from N/A
b.
[Maximum mark: 2]
19M.3.hl.TZ2.26b

Technetium-99m, Tc-99m, is a gamma-ray emitter commonly used as a medical tracer.

Its half-life is 6.0 hours.

(b)

Calculate the percentage of technetium-99m remaining after 10.0 hours. Use section 1 of the data booklet.

[2]

Markscheme

ALTERNATIVE 1

N ( t ) N 0 = ( 1 2 ) 10 6.0   [✔]
31 «% remaining» [✔]

 

ALTERNATIVE 2

λ «=  ln ⁡ 2 t 1 2 »= 0.1155 hours–1 [✔]

« N N 0  × 100 = e–λt ×100 = 0.31498 × 100»

31 «% remaining» [✔]

 

Note: M1 is for correct substitution of values.

Award [2] for correct final answer.

 

Examiners report

Most candidates were able to calculate the percentage of technetium-99m correctly.

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