Nobelium-259 has a half-life of 58 minutes. If you start with 2,000 grams of nobelium -259how long will it take to have 125 grams of nobelium- 259 left in the sample ?

Astudent is given a sample of a blue copper sulfate hydrate. he weighs the sample in a dry covered porcelain crucible and got a mass of 23.875 g for the crucible, lid, and sample. the mass of the empty crucible and lid was found earlier to be 22.652 g. he then heats the crucible to expel the water of hydration, keeping the crucible at red heat for 10 minutes with the lid slightly ajar. on colling, he finds the mass of crucible, lid, and contents to be 23.403 g. the sample was changed in the process to very light clue anhydrous cuso4. if there are again 100.0 g of hydrate, how many grams of cuso4 are in it? how many moles of cuso4? (hint: molar mass of cuso4 = 159.6 g / mole. what per cent of the hydrate is cuso4? you may convert the mass of cuso4 to moles.)

How many grams of co(g) are there in 74.5 ml of the gas at 0.933 atm and 30o c?

This classification of drug typically changes the brain's chemistry and reduces its ability to create its own endorphins.