Thorium-229 is the radioactive substance that gives lantern mantels their eerie glow. The half life of thorium-229 is 7340 years. If one mantel consists of 0.4 grams of thorium, how much thorium will remain after 14,680 years? a.
0.2

b.
0.1

c.
0.05

d.
0.8

What is the typical rotational frequency frot for a molecule like n2 at room temperature (25∘c)? assume that d for this molecule is 1å=10−10m. take the total mass of an n2 molecule to be mn2=4.65×10−26kg. you will need to account for rotations around two axes (not just one) to find the correct frequency. express frot numerically in hertz, to three significant figures.