A scientist finds a 200 gram rock composed of 150 grams of Lead-207 and 50 grams of Uranium-235. They know that the rock used to be entirely made of Uranium-235. The half-life of U-235 is 700 million years. How old is the rock?

the correct answer should be false

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imagine a line passing through the center of earth that goes through both the north pole and the south pole. this imaginary line is called an axis. earth spins around its axis, just as a top spins around its spindle. this spinning movement is called earth's rotation. at the same time that the earth spins on its axis, it also orbits, or revolves around the sun. this movement is called revolution.