Answer: The number of moles of excess reagent remain unreacted will be, 6.004 moles.
Explanation : Given,
Moles of
= 1.332 mol
Mass of
= 6.504 mol
First we have to calculate the limiting and excess reagent.
The balanced chemical equation is:

From the balanced reaction we conclude that
As, 13 mole of
react with 1 mole of

So, 6.504 moles of
react with
moles of

From this we conclude that,
is an excess reagent because the given moles are greater than the required moles and
is a limiting reagent and it limits the formation of product.
Number of moles remain unreacted = 6.504 mol - 0.5003 mol = 6.004 mol
Therefore, the number of moles of excess reagent remain unreacted will be, 6.004 moles.