Question

The potential energy $U$ between two atoms in a diatomic molecules as a function of the distance $x$ between atoms has been shown in the figure. The atoms are:

• A. attracted when $x$ lies between $A$ and $B$ and are repelled when $x$ lies between $B$ and $C$
• B. attracted when $x$ lies between $B$ and $C$ and are repelled when $x$ lies between $A$ and $B$
• C. are attracted when they reach $B$ from $C$
• D. are repelled when they reach $B$ from $A$

Answer 1

Answer: (B)

attracted when $x$ lies between $B$ and $C$ and are repelled when $x$ lies between $A$ and $B$

The atoms when brought from infinity are attracted due to inter-atomic electrostatic force of attraction. At point B, the potential energy is minimum and force of attraction is maximum. But if we bring atoms closer than x=B, force of repulsion between two nuclei starts and P.E.increases. Thus repulsive between A and B, and attractive between B and C.