Answer:
5.8 moles of copper are needed to react with sulfur to produce 2.9 moles of copper (I) sulfide.
Explanation:

Moles of copper(I) sufide = 2.9 mol
According to reaction, 1 mole of copper(I) sulfide is obtained from 2 moles of copper, then 2.9 moles of copper(I) sulfide will be obtained from :
copper
5.8 moles of copper are needed to react with sulfur to produce 2.9 moles of copper (I) sulfide.
Answer:
It has 4 valence electrons
<span> under extreme heat or pressure
crystallize from magma
precipitate from a solution reaction of hot mixture with water and a dissolved substance</span>
Your stomach will bubble lol it might kind of tickle