How many moles of nh3 can be produced from 15.0 mol of h2 and excess n2?

First, we have to write a balanced equation for the production of ammonia (NH₃) from hydrogen gas (H₂) and nitrogen gas (N₂):
                    N₂   +   3H₂   →   2NH₃

Now, the mole ratio of H₂ : NH₃ is 3 : 2 based on the coefficients of the balanced equation.

If the moles of H₂ = 15 moles

   then the moles of NH₃ produced = (15 mol ÷ 3) × 2 
                                                          =  10 mol

Thus, the number of moles of NH₃ produced when 15 mol of hydrogen gas is combined with excess nitrogen gas is 10 mol.

The correct answer should be "electrons orbit the nucleus in circular motions exactly as shown on the classic bohr model."