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

Ex Input:
Passage: A vapor light also produces visible light by electroluminescence The bulb contains a small amount of solid sodium or mercury as well as a mixture of neon and argon gases. When an electric current passes through the gases, it causes the solid sodium or mercury to change to a gas and emit visible light. Sodium vapor lights, like the streetlight pictured in the Figure below , produce yellowish light. Mercury vapor lights produce bluish light. In addition to lighting city streets, vapor lights are used to light highways and stadiums. The bulbs are very bright and long lasting so they are a good choice for these places. Answer: gas

Ex Output:
When electricity is passed through solid sodium it changes into what and gives off light?

Ex Input:
Passage: You can tell that this sponge is saturated with water because when it is squeezed, the water pours out. When something is saturated with water, it already holds as much water as possible. Compounds called hydrocarbons, which contain only carbon and hydrogen, can also be saturated, but not with water. Answer: hydrocarbons

Ex Output:
What compounds contain only carbon and hydrogen?

Ex Input:
Passage: Life Cycles of Algae: Zygotic Meiosis (A), Gametic Meiosis (B) and Sporic Meiosis (C). In life cycle A (left), diploid (2n) zygotes result from fertilization and then undergo meiosis to produce haploid (n) gametes. The gametes undergo mitosis and produce many additional copies of themselves. How are life cycles B and C different from life cycle A?. Answer: mitosis

Ex Output:
What do gametes undergo to produce many additional copies of themselves?