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Geologists know that potassium-40 decays to argon-40, with a half-life of 1.3 billion years. if an analysis of a feldspar crystal in a sample of granite shows that 75 percent of the potassium-40 atoms have decayed to form argon-40, what is the age of the granite

Look at the diagram showing the different wavelengths in sunlight. which statement describes electromagnetic waves with wavelengths greater than 700 nanometers? they take the form of heat. they can cause skin cancer and sunburn. they are some of the shortest waves. they can be seen by human eyes as visible light.

What's a recharge area? a. the part of an aquifer where groundwater meets a lake or stream b. the part of an aquifer where surface water reaches the water table c. the part of an aquifer that's located between two aquicludes d. the part of an aquifer that's located at a lower elevation