Neco Model Questions Vol1 2020 Physics Question 21

Practice objective / multiple choice question 21 from the 2020 Neco Model Questions Vol1 Physics examination.

Neco Model Questions Vol1 2020 Physics Objective / Multiple Choice Hard Difficulty
Question 21 NECO_MODEL_QUESTIONS_VOL1 • 2020 • PHYSICS • objective

A mixed radioactive sample contains isotopes A and B. Isotope A has a half‑life of 10 min and isotope B has a half‑life of 30 min. The total initial activity of the sample is \(6.0\times10^{5}\) decays min\(^{-1}\). After 20 min the measured total activity is \(2.0\times10^{5}\) decays min\(^{-1}\). Assuming both isotopes decay independently, determine the initial activity contributed by each isotope.

Answer Options

A. Isotope A: 4.00×10^5 decays min⁻¹; Isotope B: 2.00×10^5 decays min⁻¹
Correct Answer B. Isotope A: 4.68×10^5 decays min⁻¹; Isotope B: 1.32×10^5 decays min⁻¹
C. Isotope A: 3.60×10^5 decays min⁻¹; Isotope B: 2.40×10^5 decays min⁻¹
D. Isotope A: 5.00×10^5 decays min⁻¹; Isotope B: 1.00×10^5 decays min⁻¹
Correct Answer
B
Correct Option:
Isotope A: 4.68×10^5 decays min⁻¹; Isotope B: 1.32×10^5 decays min⁻¹

About This Question

This is Neco Model Questions Vol1 2020 Physics Question 21. It is one of the objective questions from the 2020 Neco Model Questions Vol1 Physics examination.

Difficulty level: Hard .

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