Argon-39 has a half-life of 269 years. how long will it take for 52.5 g of a 60.0 g sample to decay to its daughter isotope?

Which part of a feedback mechanism is able to monitor the conditions outside of cells and usually uses nerve cells to relay this information to an intergrating center

The boiling point of propanoic acid is higher than that of 1-butanol because: propanoic acid has a higher molecular weight than 1-butanol. propanoic acid is more soluble in water than 1-butanol. propanoic acid is a better hydrogen bond donor than 1-butanol. propanoic acid forms hydrogen bonded dimers and 1-butanol does not. 1-butanol forms hydrogen bonded dimers and propanoic acid does not.

How many moles is 14.5 cm^3 of platinum? the density of platinum is 21.45 g/cm^3.