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

Example Input: Passage: The composition of the magma determines if the rock is mafic, felsic, or intermediate. Answer: intermediate
Example Output: The composition of the magma determines if the rock is mafic, felsic, or what?

Example Input: Passage: The strength of bases is measured on a scale called the pH scale, which ranges from 0 to 14. On this scale, a pH value of 7 indicates a neutral solution, and a pH value greater than 7 indicates a basic solution. The higher the pH value is, the stronger the base. The strongest bases, such as drain cleaner, have a pH value close to 14. Answer: ph scale
Example Output: The strength of bases is measured on what scale?

Example Input: Passage: Chemical cells are found in batteries. They produce voltage by means of chemical reactions. Chemical cells have two electrodes, which are strips of different materials, such as zinc and carbon. The electrodes are suspended in an electrolyte. This is a substance that contains free ions, which can carry electric current. The electrolyte may be either a paste, in which case the cell is called a dry cell, or a liquid, in which case the cell is called a wet cell. Flashlight batteries contain dry cells. Car batteries contain wet cells. Answer: chemical
Example Output:
Batteries produce voltage through what type of reaction?