A zircon crystal contains atoms of and atoms of

PHYSICS · Single correct · A Level · Physics · Nuclear physics · Nuclear physics

Problem

A zircon crystal contains

3.0\times10^{17}

atoms of

^{238}\text{U}

and

4.5\times10^{17}

atoms of

^{206}\text{Pb}

. Laboratory analysis shows that

0.5\times10^{17}

of the lead atoms were present when the crystal formed. Assuming all additional

^{206}\text{Pb}

arose from the decay of

^{238}\text{U}

(half-life

4.5\times10^{9}\,\text{years}

), the best estimate of the crystal’s age is (a)

2.6\times10^{9}\,\text{years}

(b)

6.6\times10^{9}\,\text{years}

(c)

5.5\times10^{9}\,\text{years}

(d)

4.5\times10^{9}\,\text{years}