16. Which metal is used to make car bodies?
a) Aluminum
b) Iron
c) Copper
d) Silver
17. Which metal is used to make ballpoint pens?
a) Gold
b) Aluminum
c) Copper
d) Tungsten
18. Which metal is used to make water pipes?
a) Copper
b) Aluminum
c) Zinc
d) Iron
19. Which metal is used to make jet engines?
a) Aluminum
b) Iron
c) Copper
d) Titanium
20. Which metal is used to make spark plugs?
a) Copper
b) Iron
c) Zinc
d) Platinum