Neco Model Questions Vol1 2024 Physics Question 30

Practice objective / multiple choice question 30 from the 2024 Neco Model Questions Vol1 Physics examination.

Neco Model Questions Vol1 2024 Physics Objective / Multiple Choice Hard Difficulty
Question 30 NECO_MODEL_QUESTIONS_VOL1 • 2024 • PHYSICS • objective

A 2.0 g sample of a radioactive isotope X (molar mass 240 g mol⁻¹) has a half‑life of 8.0 years and decays by α‑emission to isotope Y, which itself decays by β‑emission to a stable nucleus Z. The half‑life of Y is 2.0 years. (i) Find the activity of the original X sample at t = 0. (ii) After 10 years, what is the activity of isotope Y present in the sample? (iii) What fraction of the original mass of X remains after 10 years? (Use \(N_{A}=6.022\times10^{23}\,\text{mol}^{-1}\) and \(1\,\text{yr}=3.1536\times10^{7}\,\text{s}\).)

Answer Options

A. A_X(0) = 1.38×10^13 Bq; A_Y(10 yr) = 8.0×10^12 Bq; fraction of X remaining = 0.50
B. A_X(0) = 1.20×10^13 Bq; A_Y(10 yr) = 6.5×10^12 Bq; fraction of X remaining = 0.35
C. A_X(0) = 1.50×10^13 Bq; A_Y(10 yr) = 7.1×10^12 Bq; fraction of X remaining = 0.30
Correct Answer D. A_X(0) = 1.38×10^13 Bq; A_Y(10 yr) = 7.1×10^12 Bq; fraction of X remaining = 0.42
Correct Answer
D
Correct Option:
A_X(0) = 1.38×10^13 Bq; A_Y(10 yr) = 7.1×10^12 Bq; fraction of X remaining = 0.42

About This Question

This is Neco Model Questions Vol1 2024 Physics Question 30. It is one of the objective questions from the 2024 Neco Model Questions Vol1 Physics examination.

Difficulty level: Hard .

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