The half reaction of an oxidation-reduction reaction shows that iron gains electrons. What does this electron gain mean for iron? A. It is neutralized.
B. It is oxidized.
C. It is reduced.
D. It has dissolved.
E. It has precipitated.

C. It is reduced.

Explanation:

A reduction-oxidation reaction commonly known as redox reaction is a type of chemical reaction that involves the transfer of electrons from one molecule to another. In a redox reaction, the oxidation state of atoms changes due to the donation and reception of electrons.

A redox reaction contains an oxidizing agent, which accepts the electrons and a reducing agent, which donates the electrons. The gaining of electron(s) by an oxidizing agent gets it reduced i.e. decreases its oxidation state while the donation of electron(s) by a reducing agent gets it oxidized i.e. increases its oxidation state.

In this question, the half reaction of a redox reaction is described where Iron (Fe) gains electrons. This means that iron is the oxidizing agent in this redox reaction and by gaining electrons, it becomes reduced.

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.