Which of the following acts as a strong reducing agent? (Atomic number : Ce = 58 , Eu = 63 , Gd = 64 , Lu = 71 )

Step-by-step solution

A reducing agent is one of the reactants of an oxidation-reduction reaction which reduces the other reactant by giving out electrons to the reactant. If the reducing agent does not pass electrons to other substances in a reaction, then the reduction process cannot occur. Europium (atomic number 63 ) has the electronic configuration Xe 4 f 7 6 s 2 . It loses two electrons from the 6s energy level and attains a highly stable, half-filled 4 f 7 configuration, and hence it readily forms Eu 2 + ion. Eu 2 + then changes