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 0.25 grams of thorium, how much thorium will remain after 14,680 years? a) 0.0625g b) 0.125g c) 0.25g d) 1.0g

There is a theory that indicates that dinosaurs became extinct when about 65 million years ago, a large asteroid hit the earth surface. dust caused by this collision blocked the sunlight reaching the earth's surface and many forms of life became extinct due to the cold. fearing this threat, how large the radius of an asteroid should you be looking for if the dangerous asteroid size is approximately the same as the one that killed the dinosaurs? available data suggests that about 18% of that asteroid's mass ended up as a dust spread evenly over earth after eventually settling out of the upper atmosphere. about 0.0180 g/cm^2 of dust, which is chemically different than the earth's rock, covered the earth's surface. typical asteroids have a density of about 1.9 g/cm^3. now that we know the size of the asteroid, how much energy was released during impact, assuming all of it was just the kinetic energy of the asteroid right before the impact?

In the derivation of rrkm theory, a factor of 1/2 is introduced when equalizing the rates of formation and decomposition of activated complex as keal-hr) = ko this is clearly against the assumption of transition state theory that states all the activated complex in the transition state iss going to the product. find the reason why this factor is introduced here.

If the wheels lock when braking suddenly the vehicle: a: loses traction b: lose steering wheel ability c: gain speed slightly d: gain steering ability