21. The type of glass used in making lenses and prisms is A. jena glass B. soft glass C. pyrex glass D. flint glass Show Answer Correct Answer: D. flint glass 22. Which one of the following is the petroleum wax? A. Paraffin wax B. Jonoba wax C. Carnauba wax D. Bees wax Show Answer Correct Answer: A. Paraffin wax Pages 1 2 3 4 5
