Question

Which of the following statements is true?

A) A stable bond is formed when the potential energy is zero.

B) When two atoms are very far apart, the potential energy is zero.

C) The potential energy increases as attractive forces exceed repulsive forces.

D) The bond length is the distance between the atoms when the potential energy is at its lowest point.

E) The potential energy decreases as repulsive forces increase.

Answer 1

Assuming That A and B atoms combine to for a covalent bond A-B, the bond is stable when potential energy is minimum. This is negative value (The minima in the P.E. curve) and not zero. (as shown in the diagram). So option A) is incorrect.

When two atoms A and B, are very far apart, that is the internuclear distance between them tends to infinity, than P.E. approaches zero. So option B ) is correct.

Attractive forces stabilize a molecule and decreases its potential energy. While repulsive forces increases the P.E. of molecule and makes it unstable. So option C) is incorrect. And also option E) is incorrect.

The bond length is the distance between the atoms, that is the value of internuclear separation in the curve, when the potential energy is at its lowest point. So option D) is correct.

When atoms are very close to each other, that is < bond length, than repulsive forces dominate, as shown in the figure below.

So option B) and D) are correct.

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