Task: Question Generation
Input (English): Lead crystal glassware was formerly used to store and serve drinks, but due to the potential health risks of lead, this has become rare. One alternative material is crystal glass, in which barium oxide, zinc oxide, or potassium oxide are employed instead of lead oxide. Lead-free crystal has a similar refractive index to lead crystal, but it is lighter and it has less dispersive power.
Output (English): is there such a thing as lead free crystal?