4. Which of these is most commonly used to make electric wires?
a.gold
b silver
c.copper
d.glass
5. Which of these will you not use to store acids or alkalis?
a.iron
b. ceramics
c. plastics
d. glass c. plastics
6. By measuring which of these physical properties can you definitely identify a material?
a.flexibility
b. electrical conductivity
c. strength
d, melting point