Which one of the following is a redox reaction?

Al3+(aq) + PO43-(aq) → AlPO4(s)
NaCl(aq)+ AgNO3(aq) NaNO3(aq)+ AgCl(s)
3Mg(s) + 2FeCl3(aq) → 3 MgCl2(aq) + 2Fe(s)
LiCl(aq) + AgCH3CO2(aq) → AgCl(aq) + LiCH3CO2(aq)
HF(aq) + KOH(aq) → H2O(ℓ) + KF(aq)

3Mg(s) + 2FeCl3(aq) → 3 MgCl2(aq) + 2Fe(s)

Explanation:

Redox reaction is a reduction-oxidation reaction in which oxidation states of atoms involved in the reaction are changed. The elements that receive electrons are considered to be reduced while the element that donates the electrons is considered to be oxidized. In the case of this reaction, Fe in the FeCl₃ is reduced into Fe by gaining 3 electrons - while Mg is oxidized to MgCl₂ because it donates 2 electrons.

If you check the moles of Mg, FeCl₃, Fe, and MgCl₂; you'll get to notice that the exchange of electron is balanced at 6.

c- cold periods in earth's history during which glaciers covered much of the surface.

explanation:

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.