Answer:
B. A substance that is good at reducing another atom
Explanation:
Reducing agents:
Reducing agents reduced the other element are it self gets oxidized. They have very low ionization energy and easily lose the electron.
Consider the following reactions.
4KI + 2CuCl₂ → 2CuI + I₂ + 4KCl
the oxidation state of copper is changed from +2 to +1 so copper get reduced. It means it gain one more electron.
CO + H₂O → CO₂ + H₂
the oxidation state of carbon is +2 on reactant side and on product side it becomes +4 so carbon get oxidized. Carbon loses it two more electron and act as reducing agent.
Oxidizing agents:
Oxidizing agents oxidize the other elements and itself gets reduced.
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.
