Question

A neutron having kinetic energy $5eV$ is incident on a hydrogen atom in its ground state. The collision

• A. Must be elastic
• B. Must be completely inelastic
• C. May be partially elastic
• D. Information is insufficient

Answer 1

The correct option is A Must be elastic

Hydrogen can absorb energies $10.2eV$, and others which can provide transition into higher levels.
$5eV$ cannot be absorbed.
Hence, collision is elastic, because in elastic collision kinetic energy is not converted to any other forms.