The reaction of Pb+4 and O-2 produces the compound of a
Pb2O2

b
PbO

c
Pb2O

d
PbO2

Pb₂O₄

Explanation:

The given species are:

        Pb⁴⁺               O²⁻  

Now, to solve this problem, we use the combining powers which corresponds to the number of electrons usually lost or gained or shared by atoms during the course of a chemical combination.

                                          Pb⁴⁺               O²⁻  

Combining power               4                    2

Exchange of valencies        2                    4

Now the molecular formula is  Pb₂O₄

the correct answer is:

a. formation of precipitation