Answer:
The probability that a neutron with an initial energy of 1 MeV scattered elastically from hydrogen will emerge from the scattering collision with an energy below 10 eV is not possible to determine without more information. The probability of a neutron emerging from a scattering collision with a specific energy depends on various factors, such as the type of nucleus it is scattering from, the angle and direction of the scattering, and the energy and momentum of the neutron before and after the collision.
In general, the probability of a neutron emerging from a scattering collision with a specific energy can be calculated using the Schrödinger equation, which describes the behavior of particles in a quantum system. This equation takes into account the factors mentioned above, and can be used to calculate the probability of a neutron emerging from a scattering collision with any given energy. However, without more information about the specific scattering collision in question, it is not possible to determine the probability of a neutron emerging with an energy below 10 eV.