Answer: 0.08585 moles of
is needed to produce 7.9 grams of 
Explanation: Moles is calculated by using the formula:

Molar mass of
= 46 g/mol
Number of moles of
= 0.1717 moles
For the given chemical reaction:

By Stoichiometry,
4 moles of
is produced by 2 moles of 
So, 0.1717 moles of
is produced by =
= 0.08585 moles of 
Hence, moles of
is 0.08585 moles.