In the case of radioactive element X,which decays by electron emission with a half-life of 4 days to a stable nuclide of element Z:

Question

Quizplus · Accepted Answer

Since element X has a half-life of 4 days, after 8 days, only one-fourth of the original amount of X would remain. Therefore, if 2 g of X is initially present, after 8 days, only 0.5 g of X would remain. This means that 1.5 g of X has decayed to form element Z. Therefore, choice A is correct.

Choice B is incorrect because the loss of electrons during decay does not affect the mass of the element.

Choice C is incorrect because although Z may have a higher atomic number, it does not necessarily mean that it will weigh more than X after decay.

Choice D is incorrect because after 8 days, only one-fourth of the sample would consist of element Z while three-fourths would still be element X.

Choice E is incorrect because even after 8 days, only a portion of element X would have decayed to form element Z, not the entire amount.

In the Case of Radioactive Element X,which Decays by Electron