Balance by algebric (abcd) method
NO2 十O2 →N2O5

Sulfuric acid (a component of acid rain) reacts with limestone (calcium carbonate) to produce calcium sulfate and carbon dioxide. this damages buildings and statues made of limestone. which solution of sulfuric acid will damage these structures more quickly? a. 0.001% b. 0.005% c. 0.010% d. 0.015%

How do you know when a chemical reaction has occurred

Ablock of aluminum is dropped into a graduated cylinder with an initial volume of water at 75ml and the volumes rises to 90ml. if the block has a mass of 40.5 g what is its density ?