Matter is frequently classified according
to its electrical conductivity as a conductor, insulator,
or semiconductor. Conductors have many electrons that are
free to move and are useful in carrying, electric current.
All metals, particularly silver and copper are good conductors.
Substances with few free electrons are called insulators,
because they do not carry electric charge and can be used
to prevent electricity from flowing. Air, wood and plastic
are insulators. A few substances, like carbon, silicon, do
not fall into either of these categories. They are classed
as semiconductors and are used in such electronic devices
as transistor radios.
(99 words)
Which of the following is the most suitable title for this
passage?
A) Structure of Matter
B) Electrical Conductivity
C) The Functions of Insulators
D) The Functions of Conductors
Level
1 
