Every known element has

• the same type of atoms

• the same number of atoms

• a unique type of atom

• several different types of atoms

An atom consists of

• one nucleus and only one electron

• one nucleus and one or more electrons

• protons, electrons and neutrons

• answer (b) and (c)

The nucleus of an atom is made up of

• protons and neutrons

• electrons

• electrons and protons

• electrons and neutrons

Valence electrons are

• in the closest orbit to the nucleus

• in the most distant orbit from the nucleus

• in various orbits around the nucleus

• not associated with a particular atom

The most widely used semi-conductive material in electronic device

• germanium

• carbon

• cooper

• silicon

The energy band in which free electrons exist is the

• first band

• second band

• conductive band

• valence band

The current in a semiconductor is produced by

• electron only

• holes only

• negative ions

• both electrons and holes

The process of adding an impurity to an intrinsic semiconductor is called

• doping

• recombination

• atomic modification

• ionization

The majority carrier in an n-type semiconductor are

• holes

• valences electrons

• conduction electrons

• protons

A pn junction is formed by

• the recombination of electrons and holes

• ionization

• the boudary of a p-type and an n-type material

• the collision of a proton and a neutron