A) An isotope of uranium-238 decays by alpha emission. The half life of this isotope is 30 years. The sample was left to decay over a period of 240 years in ambient condition. After 240 years, the alpha decay of uranium-238 isotope resulted in the production of alpha particles and the element, with a proton number of and a mass number of B) An isotope of uranium-238 has a half-life of 30 years. If 1.00 x 106 kg of uranium-238 disintegrates over a period of 240 years, how many micrograms of uranium-238 would remain?