A radioactive isotope has an initial mass of

CHEMISTRY · Multi-part · US High School · Chemistry · Atomic Structure & Nuclear · Atomic Structure & Nuclear

Problem

10\,\text{g}

. After

5\,\text{years}

its mass has decreased to

7.5\,\text{g}

. (i) Formulate the differential equation governing the mass

N(t)

of the isotope at time

t

years, defining all symbols used. (ii) Using the given data, determine the decay constant

\lambda

correct to four decimal places. (iii) Find the half-life of the isotope, giving your answer to two decimal places. (iv) How much of the isotope will remain after

20\,\text{years}

? Express your answer correct to one decimal place.

Related theory

Chemical Kinetics

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