Statement-1: Two particles moving in the same direction do not lose all their energy in a completely inelastic collision.Statement-2: Principle of conservation of momentum holds true for all kinds of collisions.

Statement-1: In a completely inelastic collision, the particles stick together. If they move in the same direction, the total momentum is non-zero. Since momentum is conserved, the final velocity of the combined mass must be non-zero. If final velocity is non-zero, final kinetic energy is non-zero. Thus, they cannot lose all their energy. (True)Statement-2: Conservation of momentum is a fundamental law valid for all internal interactions, including all types of collisions. (True)Statement-2 explains why the final velocity isn't zero, which in turn explains Statement-1.