Chemistry
posted by Jacob .
The halflife of hafnium156 is 0.025 s. how long will it take a 560 g sample to decay to onefourth it's original mass?

Chemistry 
DrBob222
See above to one of your other screen names.

Chemistry 
David
Dr. Bob, I don't need ur criticism now!! I need your help to resolve these problems

Chemistry 
DrBob222
I assure you there was no criticism. Those equations I gave you above will do them all. If you have further problems, please explain what you don't understand and we can help you through. You must understand that this is a help board and if we show you how to do one problem, then the others like that one can be done on your own. And for what it's worth, keeping the same screen name helps us help you faster and with better results.
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