Radon-222 has a decay constant of 0.181day−1. Thoron (radon-220) has a half-life of 54.5s. A sealed container initially holds equal numbers of nuclei of the two gases.
(i) Find the half-life of radon-222 in hours.
(ii) Calculate the ratio of the numbers of undecayed nuclei of radon-222 to thoron remaining after 5.0minutes.
(iii) Based on your result, state which gas is more suitable for long-term radiation tests and justify your choice.