Question

A neutron having KE 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

For a collision ofneutron with hydrogen atom in ground state to be inelastic ( partial or complete) the minimum KE ofstriking neutron must be 20.4 eV. [ This condition can be proved by using basic concepts]. As the energy of given incident neutron is less than 20.4eV the collision must be elastic.