JEE Advanced 2022 Physics question

A disk of radius R with uniform positive charge density is placed on the plane with its center at the origin. The Coulomb potential along the -axis is

V(z) = ( - z).

A particle of positive charge is placed initially at rest at a point on the axis with and . In addition to the Coulomb force, the particle experiences a vertical force with . Let . Which of the following statement(s) is(are) correct?

• (A)For and , the particle reaches the origin.Correct
• (B)For and , the particle reaches the origin.
• (C)For and , the particle returns back to .Correct
• (D)For and , the particle always reaches the origin.Correct