Question

In an atom, electrons ____.
are located in the nucleus
are paired with neutrons
travel outside the nucleus
are always in the same place in an atom

Answer 1

The atomic structure is in such a way so as to give electrical neutrality to the atom.
For that the positive protons and neutral neutrons are packed together inside a high density nucleus. This is the place where maximum mass of the atom is concentrated.

The electrons revolve round the nucleus in different quantum levels as per the energy they posses. This revolution is analogous the planets revolving around the sun. Here the electric energy is the one that keeps protons (in the nucleus) and the electrons (revolving around it) bind to give stability to the atom. Also to maintain the charge neutrality of the atom as a whole, the number of electrons is equal to the number of protons.

So, short answer to this question is "travel outside the nucleus"

Answer 2

In an atom, electrons ____.

A.) are located in the nucleus

Can't be A, electrons are not located in the nucleus, but rather protons and neutrons.

B.) are paired with neutrons

Can't be B, neutrons are not outside the nucleus.

C.)travel outside the nucleus

Probably Yes. Orbiting in a cloud around the nucleus.

D.) are always in the same place in an atom

No, because they are traveling around 99% the speed of light.