Can anyone please explain me that how it is possible when same force is applied for the same time on different bodies of different mass then still same change in momentum takes place

Comes from good old Mr. Newton:

F \Delta t = \Delta (mv) = change in momentum.

Thus applying a given force for a given period resuts in a specific change in momentum to the object in question. If the object has a large mass it's change in velocity will be relatively small, but its change in momentum is the same as for a small mass.