How me and other scientists know about animals that went extinct for million people million of years ago

As you move from right to left on the periodic table the atomic radius fill in the blank

Which statement describes james chadwick’s discovery.

Achemist 16 drop copper metal from copper chloride solution. the chemist place is 0.50 g of aluminum foil in a solution containing 0.75 g of copper (ii) chloride. a single replacement reaction takes place. which statement explains the maximum amount of copper that the chemist can extract using this reaction?