How many half lives would have passed if only 6.25% is still radioactive?

Check all that apply diatoms are marine algae that have a shell made of silica, what are some of the uses of the silica shell after the diatoms die? 1.the shells make up the diatomaceous earth used in filters 2.it can be used as an ingredient in abrasives 3.they are used in food products 4.the shells can be used in some insulating materials

According to your text, should be in the native language of the parents or guardians whenever possible. a. an email b. consent forms c. oral approval d. storybooks loaned out

Diagram of the evolution of land plants?