Question

1. A skeleton is discovered buried in a field near your house. A sample of bone from the skeleton contains 10 g of ¹²C and 2.5×10^-12 g of ¹⁴C. How old, to within 20%, is the skeleton?

(a) 6000 years (b) less than 100 years (c) 12,000 years (d) 3000 years

2. The half-life of ²³⁵U is 700 million years. A piece of very old rock now contains 0.2 g of ²³⁵U. To 10% accuracy, how much ²³⁵U was there in the rock when it was formed on earth 4 billion years ago?

(a) 60 g (b) 6 g (c) 0.3 g (d) 10 g

Answer 1