Answer: The number of moles of hydrogen gas that will be produced is 15.0 moles.
Step-by-step explanation:
We are given:
Moles of aluminum needed to be dissolved = 10.0 moles
For the given chemical reaction:

By Stoichiometry of the reaction:
2 moles of aluminium produces 3 moles of hydrogen gas
So, 10.0 moles of aluminium will produce =
of hydrogen gas
Hence, the number of moles of hydrogen gas that will be produced is 15.0 moles.