Neco Model Questions Vol1 2018 Physics Question 37
Practice objective / multiple choice question 37 from the 2018 Neco Model Questions Vol1 Physics examination.
A 2.0 g sample of a radioactive isotope X (atomic mass \(120\ \text{u}\)) has a half‑life of \(8.0\) days and emits \(\gamma\)-rays of energy \(0.5\ \text{MeV}\). (i) Calculate the activity of the sample after \(5.0\) days (express your answer in becquerels, Bq, to two significant figures). (ii) To reduce the \(\gamma\)-ray intensity to \(30\%\) of its original value, a lead shield is used. The mass‑attenuation coefficient of lead for \(0.5\ \text{MeV}\) \(\gamma\)-rays is \(0.12\ \text{cm}^{2}\text{g}^{-1}\) and the density of lead is \(11.34\ \text{g\ cm}^{-3}\). Determine the minimum thickness of lead required (in cm, correct to two decimal places).
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About This Question
This is Neco Model Questions Vol1 2018 Physics Question 37. It is one of the objective questions from the 2018 Neco Model Questions Vol1 Physics examination.
Difficulty level: Hard .
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