Given a scientific passage and an answer, generate a question for the given answer.

Input: Consider Input: Passage: There are no forces of attraction or repulsion between gas particles . Attractive forces are responsible for particles of a real gas condensing together to form a liquid. It is assumed that the particles of an ideal gas have no such attractive forces. The motion of each particle is completely independent of the motion of all other particles. Answer: superscripts

Output: Which measure indicates the number of electrons in a given sublevel?

Input: Consider Input: Passage: Sliding friction is friction that acts on objects when they are sliding over a surface. Sliding friction is weaker than static friction. That's why it's easier to slide a piece of furniture over the floor after you start it moving than it is to get it moving in the first place. Sliding friction can be useful. For example, you use sliding friction when you write with a pencil. The pencil "lead" slides easily over the paper, but there's just enough friction between the pencil and paper to leave a mark. Answer: sliding friction

Output: What type of friction is friction that acts on objects when they are sliding over a surface?

Input: Consider Input: Passage: The angular velocity tells you how quickly the angle changes. In more formal language, the rate of change of , the angular position, is called the angular velocity . The direction of angular velocity is either clockwise or counterclockwise. Analogously, the rate of change of is the angular acceleration . Answer: angular velocity
Output: What term tells you how quickly the angle changes and can occur in either clockwise or counterclockwise directions?