Answer: The number of moles of hydrogen chloride produced are 20 moles.
Step-by-step explanation:
For the reaction of hydrogen chloride from hydrogen and chlorine, the equation follows:

By Stoichiometry of the reaction:
1 mole of hydrogen produces 2 moles of hydrogen chloride.
So, 10 moles of hydrogen will produce =
moles of hydrogen chloride.
Hence, the number of moles of hydrogen chloride produced are 20 moles.