2. How many moles of copper are needed to react with sulfur to produce 0.25 moles of
copper(t) sulfide according to the following reaction:
2 Cu + S + Cu2S

0.5

Explanation:

Cu       Cu2S

2   :       1 ratio

therefore  0.25 moles of Cu2S * (2 moles of Cu/ 1 mole of Cu2S)

=0.5 moles of Cu

- decrease the number of plants and animals living in the water.

the positions which points up in upward carbon and down in downward carbon are axial

and vice versa holds true for equatorial positions

so the correct answer with labelled diagram will be