A wooden artifact from an ancient tomb contains 30 percent of the carbon -14 that is present in living trees. How long ago, to the nearest year, was the artifact made?( The half-life of carbon-14 is 5730)

A wood carving is found in the excavation of an abandoned settlement. A sample from this carving is found to have a C-14 content that is 25.0% of that of living trees. How old is the object? The half-life of carbon 14 is 5730 years.

The half-life of carbon-14 is about 5730 years. If an ancient leather strap is about 11,500 years old, what percentage of carbon-14 in a now-living object remains in the strap? O 100% 50% O 25 % none O O O O

A volcanic eruption melts a large chunk of rock, and all gases are expelled. After cooling, argon-40 accumulates from the ongoing decay of potassium-40 (half-life of potassium-40 is 1.25 x 109 yr) in the rock. When a piece of rock is analyzed, it is found to contain 1.38 mmol of potassium-40 and 1.14 mmol of argon-40. How long ago did the rock cool?