16. Who discovered the principle of natural selection?
A) Charles Darwin
B) Gregor Mendel
C) Louis Pasteur
D) Robert Koch
Answer: A) Charles Darwin
17. What is the name of the process by which water changes from a liquid to a gas?
A) Melting
B) Freezing
C) Boiling
D) Condensation
Answer: C) Boiling
18. Who discovered the law of electromagnetism?
A) James Clerk Maxwell
B) Michael Faraday
C) Isaac Newton
D) Hermann von Helmholtz
Answer: A) James Clerk Maxwell
19. Who discovered the first successful polio vaccine?
A) Albert Sabin
B) Jonas Salk
C) Robert Koch
D) Louis Pasteur
Answer: B) Jonas Salk
20. What is the name of the process by which water changes from a gas to a liquid?
A) Melting
B) Freezing
C) Boiling
D) Condensation
Answer: D) Condensation
