What is the total number of years that must pass before only 25 g of an original 100 sample of C-14 remains uncharged

How can parts of a solution be separated by chromatography?

List and describe the neurological effects of the vocs and other air pollutants,as described by dr.theo colborn

Polar bears give birth and hunt on sea ice. which of the following would polar bears survive during the melting of arctic ice? growing another layer of fur during summer migrate inland to search for different food sources staying put until the ice refreezes sticking to the usual diet of seals