Which soil cannot be rolled into balls or clumps

Your answer would be Sand.

If you go to the beach, and try making balls in your hand it's nearly impossible. If you pick up sand it will just fall through the crevice's in your hand, or a simple movement of your hand can make the sand fall. Sand simply can't be formed into a ball.

If you where to try making a ball of sand the outcome wouldn't be great. Even if you made the sand damp you still can't really make a ball of sand.

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.