Physics

Problem

A geologist wishes to determine the age of a rock believed to be about

3\,\text{billion}

years old. Which radioactive isotope is the most suitable for this purpose? a)

^{14}\text{C}

(half-life

=5.73\times10^{3}\,\text{yr}

) b)

^{238}\text{U}

(half-life

=4.5\times10^{9}\,\text{yr}

) c)

^{40}\text{K}

(half-life

=1.25\times10^{9}\,\text{yr}

) d)

^{235}\text{U}

(half-life

=7.1\times10^{8}\,\text{yr}

)