The decay of 40K to 40Ar is used to date igneous rocks around fossil deposits to bracket the age of the fossils. When 40K decays, 10.9% of the time it produces 40Ar. The half-life of 40K is 1.248 x 109 years. In a given rock sample, 281.8 nmol of 40K is measured and 7.25 nmol of 40Ar is measured. What is the age of the rock in years

Engineers have contribute to society in many ways like making the technology we use today or any type of power energy material

The population of unionid mussels decreased after zebra mussels were introduced. zebra mussels competed with the unionid mussels for food. the zebra mussels were able to displace the unionid mussels, allowing the zebra mussel population to increase  over the years. the unionid mussel population decreased because  of lack of food.

1. why does the same side of the moon always face earthc.the rotational period of the moon is equal to one revolution around earth2. which is greater the moons period of rotation or its period of revolution  b.the moons revolution period around earth3.what was the major accomplishment of the apollo missions  c.sending the first human into space4. which of these space missions involved the deployment of lunar roversa. voyager 15. which scientists are going to explore next on kepler-186fd. evidence of existence of life6.which mission is not going to explore the outside of the solar  systemb.safir7.which technology limit the future of space explorationb. scientist must first develop certain technologies before missions can be completed.