11. What do columns in the periodic table represent?

A. periods
B. groups
C. representative elements
D. transition metals

12. Silicon is a semiconductor and has properties of both metals and nonmetals. What type of element is silicon?

A. metal
B. metalloid
C. nonmetal
D. none of the above

13. Which among the following statements best describes a compound?

A. It is made of only one element.
B. It cannot be broken down into simpler substances.
C. Its examples include Silicon, Magnesium and Tin.
D. It is normally represented by a chemical formula.

14. How many different atoms are there in a compound?

A. no atoms
B. one
C. always two
D. two or more

15. Iodine, bromine, and chlorine are examples of nonmetals. What best distinguishes a nonmetal from a metal?

A. brittle
B. ductile
C. malleable
D. poor conductors​