Engineers test the safety of a new car by running a crash test, which shows whether the airbags inflate properly. When the car detects a crash, a small amount of sodium azide (NaN3) stored behind each airbag is heated. The sodium azide breaks down into sodium metal (Na) and nitrogen gas (N2). The nitrogen gas inflates the airbags in less than one-tenth of a second! This design helps to keep people inside cars from getting seriously injured in a crash. In the chemical reaction described in the passage, which of the following are reactants?