Question

The orbitals involved in the formation of sigma bond are s-s, s-p, p-p And the orbitlas involved in the formation of pi bond is p-p orbitals . Now how do i understamd when the p-p bond forms pi bond or sigma bond ?

Answer 1

In a sigma  bond is formed by the end to end overlap of bonding orbitals 
AXIAL OVERLAP
in a pi bond their axes remain parallel to each other --- sidewise

you can look the diagram to understand well