31. Who discovered the principle of relativity?
a) Galileo Galilei
b) Isaac Newton
c) Albert Einstein
d) Stephen Hawking
Answer: c) Albert Einstein
32. Who invented the steamboat?
a) Robert Fulton
b) George Stephenson
c) Richard Trevithick
d) James Watt
Answer: a) Robert Fulton
33. Who discovered the theory of evolution by natural selection?
a) Charles Darwin
b) Gregor Mendel
c) Thomas Hunt Morgan
d) James Watson
Answer: a) Charles Darwin
34. Who invented the sewing machine?
a) Elias Howe
b) Isaac Singer
c) Thomas Edison
d) Alexander Graham Bell
Answer: a) Elias Howe
35. Who discovered the law of buoyancy?
a) Archimedes
b) Isaac Newton
c) Galileo Galilei
d) Leonardo da Vinci
Answer: a) Archimedes
