Ten grams of ⁵⁷ Co is placed in an open container and undergoes beta-decay with a half-life of 270 days . After 540 days , the weight of the material inside the container will be approximately

Step-by-step solution

In -decay, the mass number of the nucleus remains unchanged. The parent nucleus ⁵⁷ Co decays into a daughter nucleus which is also a solid and remains in the open container. The mass of the emitted -particles and the mass equivalent of the energy released are negligible compared to the total mass of the material. Thus, the atomic mass of the daughter nucleus is approximately equal to that of the parent nucleus. After 540 days (which corresponds to exactly two half-lives, since T_ 1/2 = 270 days ), the mass of ⁵⁷ Co