Help!! 1.Approximately what percentage of the isotope remains after 80 days?

2.What is the half-life of the isotope shown on the graph?

3.How long would it take a 20 g sample of Thorium-234 to decay into only 5 grams of Thorium-234?

13. a covalent bond between two atoms is likely to be polar if: a. one of the atoms is much more electronegative than the other. b. the two atoms are equally electronegative. c. the two atoms are of the same element. d. the bond is part of a tetrahedrally shaped molecule. e. one atom is an anion.

What is bromine+calcium iodide--> calcium bromide +iodine balanced

Select the correct answer from each drop-down menu. to make a table of the elements, dmitri mendeleev sorted the elements according to their . he then split the list of elements into several columns so that elements beside each other had similar .