Answer:
Cu
Fe
Explanation:
Oxidizing agents:
Oxidizing agents oxidize the other elements and itself gets reduced.
Reducing agents:
Reducing agents reduced the other element are it self gets oxidized.
Oxidation:
Oxidation involve the removal of electrons and oxidation state of atom of an element is increased.
Reduction:
Reduction involve the gain of electron and oxidation number is decreased.
a) Cu²⁺ (aq) + Mg(s) + Cu(s) + Mg²⁺(aq)
Copper is oxidizing agent it accept two electrons from magnesium and oxidize the Mg and itself get reduced.
b) Fe₂O₃(s) + 3CO(g) → 2Fe(l) + 3CO₂(g)
In this reaction iron is oxidizing agent because iron itself reduced from +3 to 0.
The question is incomplete, complete question is :
A chemist must dilute 73.9 mL of 400 mM aqueous sodium carbonate solution until the concentration falls to 125 mM . He'll do this by adding distilled water to the solution until it reaches a certain final volume. Calculate this final volume, in liters. Be sure your answer has the correct number of significant digits.
Answer:
The final volume of the solution will be 0.236 L.
Explanation:
Concentration of sodium carbonate solution before dilution =
Volume of sodium carbonate solution before dilution = 
Concentration of sodium carbonate solution after dilution =
Volume of sodium carbonate solution after dilution = 
Dilution equation is given by:



1 mL = 0.001 L
236 mL = 0.236 L
The final volume of the solution will be 0.236 L.
It stops producing electricity