Definition: Given a scientific passage and an answer, generate a question for the given answer.
Input: Passage: Elemental bromine gas can be generated by reacting sodium bromide with elemental chlorine. The other product is sodium chloride. Write a balanced chemical equation for this reaction. Saylor URL: http://www. saylor. org/books. Answer: elemental bromine gas
Output:
What gas can be generated by reacting sodium bromide with elemental chlorine?