Hydrogen and oxygen react under a specificset of conditions to produce water accordingto the equation2 H2(g) + O2(g) −→ 2 H2O(g).How much hydrogen would be required toproduce 3.9 mol of water?Answer in units of mol.

Which of the following is an indication that a substance has undergone a chemical change? a. no new product has been formed. b. the color of the substance has not changed. c. the original constitute has not changed. d. the molecular structure has changed.