Strong reducing and oxidizing agents among the following, respectively, are

A strong reducing agent is a species that readily loses electrons (gets oxidized). A strong oxidizing agent readily gains electrons (gets reduced).

Eu$$^{2+}$$ is a strong reducing agent because europium prefers the +3 oxidation state (half-filled 4f⁷ configuration). Eu²⁺ readily loses an electron to become Eu³⁺.

Ce$$^{4+}$$ is a strong oxidizing agent because cerium prefers the +3 oxidation state. Ce⁴⁺ readily gains an electron to become Ce³⁺ (which has a noble gas core [Xe] configuration).

Therefore, the strong reducing agent is Eu$$^{2+}$$ and the strong oxidizing agent is Ce$$^{4+}$$.

The correct answer is Eu$$^{2+}$$ and Ce$$^{4+}$$.