Which sequence of atomic numbers represents elements which have similar chemical properties? a
b
4, 20, 38,88
3, 12, 21, 40
9, 16, 33,50
19, 23, 30, 36
d

Flourine is found to undergo 10% radioactivity decay in 366 minutes determine its halflife

Which of the following observations indicates that there is a small, dense, positively charged part in the center of an atom? some uncharged particles are scattered by a gold foil. all uncharged particles are attracted towards a gold foil. all positively charged particles pass straight through a gold foil. some positively charged particles bounce back from a gold foil.

Which common material is an example of a polymer? (25 pts) a. steel b. plastic c. petroleum d. rubbing alcohol