Answer:
Reactants: hydrogen and oxygen
Products: water
Step-by-step explanation:
The reactants are what goes into a reaction, i.e. what is reacting. The products are what is formed. The reactants are usually shown on the left, and the products are usually shown on the right.
We can see in this equation that hydrogen (2H2) is reacting with oxygen (O2) to form water (2H2O). Therefore the reactants are hydrogen and oxygen, and the product is water.