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Question 18N.3.hl.TZ0.22b.i

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Date November 2018 Marks available [Maximum mark: 2] Reference code 18N.3.hl.TZ0.22b.i
Level hl Paper 3 Time zone TZ0
Command term Calculate Question number b.i Adapted from N/A
b.i.
[Maximum mark: 2]
18N.3.hl.TZ0.22b.i

Nuclear isotopes are used in the treatment of cancer.

Gamma radiation is also used in radiotherapy.

(b.i)

Technetium-99m ( 43 99 m Tc ) has a half-life of 6.0 hours. Calculate the percentage of  43 99 m Tc  remaining in a sample of the radioisotope after two days.

[2]

Markscheme

ALTERNATIVE 1:

« 40 6.0 =» 8  t 1 2 /8 half-lives «required» ✔

% remaining = «(0.5)8 × 100 =» 0.39 «%» ✔

 

ALTERNATIVE 2:

λ = « 0.693 6.0 =» 0.1155 ✔

% remaining = «100 × e–0.1155 × 48 =» 0.39 «%» ✔

 

Award [2] for correct final answer.

Accept “0.32 «%»” in ALTERNATIVE 2.

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