1. What was the name of the medieval pandemic that killed millions in Europe?

2. The Declaration of Independence was signed in which city?

3. Who was the first President of South Africa elected after apartheid?

4. Which empire was ruled by Genghis Khan?

5. What was the original primary use for the first wheels invented in Mesopotamia?

6. What material is most commonly used as the substrate for integrated circuits?

7. At which research organization did Tim Berners-Lee invent the World Wide Web?

8. Whose hand was the subject of the first-ever medical X-ray image?

9. What does a lightning rod do with the electrical charge from a strike?

10. How does a diesel engine ignite its fuel without using a spark plug?

11. What was the first commercial product made using nylon?

12. What was the original purpose of Willis Carrier's first air conditioning system?

13. How did the first commercial vacuum cleaner, the 'Puffing Billy,' collect dust?

14. What was the revolutionary dual-power system used in John Philip Holland's submarine?

15. What major era in American history did the invention of barbed wire effectively end?

16. What was the first major practical application for the silicon solar cells invented in the 1950s?

17. What was the name of the top-secret U.S. project that developed the first atomic bomb?

18. What does the acronym UAV stand for in the context of drone technology?

19. What color LED was the final 'missing link' needed to create white LED light for general illumination?

20. What is the primary characteristic of a blockchain ledger?