3077

Physics Modern Physics Level: High School

Radioactivity

44 g of petrified wood was found in a petrified forest . A sample showed a 14 C activity of 100 decays / minute . How long has the tree been dead (in years) ? (The half-time of carbon -14 is 5730 years and freshly cut wood contains 6.5 x 1010 atoms of 14 C per gram) .

a) 32,300

b) 15,600

c) 8,500

d) 4,700

e) 2,400