Final answer:
The strong electrolytes from the options given are NaOH (sodium hydroxide), NaBr (sodium bromide), and CaCl2 (calcium chloride), as they completely dissociate into ions in solution.
Step-by-step explanation:
The question asks which of the given substances are strong electrolytes. Strong electrolytes dissociate completely in solution, leading to the formation of ions that can conduct electricity. The substances listed that are strong electrolytes include NaOH (sodium hydroxide), NaBr (sodium bromide), and CaCl2 (calcium chloride). Sodium hydroxide dissociates into sodium ions (Na+) and hydroxide ions (OH-), sodium bromide into sodium ions (Na+) and bromide ions (Br-), and calcium chloride into calcium ions (Ca2+) and chloride ions (Cl-). On the other hand, benzene (C6H6) does not dissociate into ions in solution and therefore is classified as a nonelectrolyte. Thus, the correct choices for strong electrolytes are NaOH, NaBr, and CaCl2.