Neco Model Questions Vol1 2023 Physics Question 39

Practice objective / multiple choice question 39 from the 2023 Neco Model Questions Vol1 Physics examination.

Neco Model Questions Vol1 2023 Physics Objective / Multiple Choice Hard Difficulty
Question 39 NECO_MODEL_QUESTIONS_VOL1 • 2023 • PHYSICS • objective

A sample of a radioactive isotope X decays by beta emission with a half‑life of \(2.0\ \text{h}\). Its initial activity is \(5.0\times10^{3}\ \text{Bq}\). (i) After a period of \(3.0\ \text{h}\), how many undecayed nuclei remain in the sample? (ii) Beta particles of this isotope are to be attenuated to \(5\%\) of their original intensity using a lead shield. The mass attenuation coefficient for the beta particles in lead is \(0.12\ \text{cm}^{2}\,\text{g}^{-1}\) and the density of lead is \(11.34\ \text{g cm}^{-3}\). What thickness of lead (in cm) is required? Take \(\ln 2 = 0.693\).

Answer Options

Correct Answer A. Remaining nuclei ≈ 1.8×10^7; Lead thickness ≈ 2.20 cm
B. Remaining nuclei ≈ 1.2×10^7; Lead thickness ≈ 3.10 cm
C. Remaining nuclei ≈ 2.5×10^7; Lead thickness ≈ 1.80 cm
D. Remaining nuclei ≈ 3.0×10^7; Lead thickness ≈ 2.80 cm
Correct Answer
A
Correct Option:
Remaining nuclei ≈ 1.8×10^7; Lead thickness ≈ 2.20 cm

About This Question

This is Neco Model Questions Vol1 2023 Physics Question 39. It is one of the objective questions from the 2023 Neco Model Questions Vol1 Physics examination.

Difficulty level: Hard .

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