The given plot shows the variation of U, the potential energy of interaction between two particles with the distance r separating them.

a) B and C are equilibrium points
b) C is a point of stable equilibrium
c) The force of interaction between the two particles between D and E
d) The force of interaction between particles is repulsive between points E and F.
Which of the absove statements are correct
1) a and b 2) a and d 3) b and d 4) b and c

Explanation

The corresponding F - r graph is shown below

If particle at C is displaced either of the side, the force will bring it back to C. Hence .C. is a point of stable equlibrium. Force on a particle at D is negative, it is directed towards C and is directed away from D. Hence force of interaction is attractive between C and D while repulsive between D and E.