21. Which metal is commonly used for making electrical contacts and connectors due to its high conductivity and resistance to corrosion?
a) Copper
b) Aluminum
c) Silver
d) Nickel
22. What is the process of shaping metal by pouring molten metal into a mold and allowing it to solidify called?
a) Casting
b) Forging
c) Extrusion
d) Machining
23. Which metal is primarily used for making aircraft engines and gas turbines due to its high strength-to-weight ratio?
a) Copper
b) Aluminum
c) Iron
d) Titanium
24. What is the process of reducing the size of metal ore particles by crushing and grinding called?
a) Refining
b) Smelting
c) Milling
d) Concentration
25. Which metal is primarily used for making electrical transmission lines due to its low resistance and cost-effectiveness?
a) Copper
b) Aluminum
c) Iron
d) Silver
