When the earth was rst formed from an enormous disk of gas and dust about 4.5 billion years ago (see


When the globe was rst formed from an colossal disk of gas and clay environing 4.5 billion years ago (see Chapter 9), the attention of U-235 was abundant upper in the globe’s covering than it is today. If the attention of U-235 in the globe’s covering today is 1.5 compressiveness per 100 darling, what was the attention of U-235 in the globe’s covering approximately 4.25 billion years ago?