What are the signs you can see that would show you a chemical reaction has occurred?

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.

Calculate the molarity of each aqueous solution: a. 78.0 ml of 0.240 m naoh diluted to 0.250 l with water b. 38.5 ml of 1.2 m hno3 diluted to 0.130 l with water

2ki + pb(no3)2 → 2kno3 + pbi2 determine how many moles of kno3 are created if 0.03 moles of ki are completely consumed.