Out of gravitational, electromagnetic, Vander Waals, electrostatic and nuclear forces; which two are able to provide an attractive force between two neutrons

Two identical conducting spheres $A$  and $B,$  carry equal charge. They are separated by a distance much larger than their diameter, and the force between them is $F$ . A third identical conducting sphere, $C,$  is uncharged. Sphere $C$  is first touched to $A,$ then to $B,$  and then removed. As a result, the force between $A$  and $B$  would be equal to

Two equal negative charge $-q$ are fixed at the fixed points $(0,\,a)$ and $(0,\, - a)$ on the $Y$-axis. A positive charge $Q$ is released from rest at the point $(2a,\,0)$ on the $X$-axis. The charge $Q$ will

The electric field between the two spheres of a charged spherical condenser

Two charges each of $1\;coulomb$ are at a distance $1\,km$ apart, the force between them is

A proton is fired at an initial velocity of $150 \,m/s$ at an angle of $60^o $ above the horizontal into a uniform electric field of $2 \times 10^{-4} \,N/C$ between two charged parallel plates as shown in figure. Then the total time the particle is in motion is :-