a neutron moving with velocity v collides with a stationary alpha particle. the velocity of the neutron after the collision is.?

Alpha particles are He nuclii therefore have 2neutrons and 2protons. Mass of proton and neutron are almost equal. So mass of alpha particle =4m if mass of 1neutron is m. So velocity of neutron after collision should be -3/5 v.

it will be reduced to v/2 , since it acts on a mass!!