Bump
No, it cannot
low
You should pass (bump) the volleyball when it is below your shoulders. You will get the best contact with the volleyball this way.
Putting hands toghether with your two thums pointing could be used for bumping or serving
It's used to center the ball, so that a teammate may easily redirect it.
The forearm usually used in blocking consists of two bones, the Ulna and the Radius.
The whole of the skeletal frame is used in the game. The joints in arms legs and back are the most stressed.
The pass is usually used to direct the ball to the setter, so that the setter can set the ball to the hitter, and the hitter can spike it on to the opponent's side.
A bump is when you pass the ball with your forearm, often used to receive a hard serve, or a ball that is too low to pass on above your head, and is one of the basic skills to master in Volleyball. A bump is usually the first pass which goes to the setter for a hitter to hit it over. The precision of the bump is not the best, so to prepare an attack (with a spike) i.e. to "set", an overhand pass i preferred, with the fingertips. To bump, you put your hands together, thumb to thumb, closing one fist on the other to form a "ball". Then the incoming ball is hit from below with a distinct impact, and may gain high velocity. A bump is also called a forearm pass or just a pass, but is sometimes used as well to hit the ball to the opponents' court side, as a weak "attack".
Biceps and forearm muscles are used
Underhand Pass (or simply pass)- used primarily in the backrow for defensive specialists. The goal is to get up to the setter. Overhand Pass (set)- used primarily by the setter. The goal is to set it up for a hitter to hit it.