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Q.
The diagrams represent the potential energy $U$ of a function of the inter-atomic distance $r.$ Which diagram corresponds to stable molecules found in nature?
Work, Energy and Power
Solution:
When the distance between atoms is large then interatomic force is very weak. When they come
closer, force of attraction increases and at a particular distance force becomes zero. When they are further brought closer force becomes repulsive in nature. This can be explained by slope of $U-x$ curve shown in graph (a).