Which of the following describes an independent variable?
answer= controlled by the experimenting scientist.(apex)

The best sentence that describe an independent variable would be : The factor in an experiment that could be deliberately changed.
The scientist use deliberately change this factor to find out which factor actually caused the occurrence in the experiment.

Hope this helps

The proton has a positive charge while the neutron has no charge they both make up the nucleus of the atom while the elections have a negative charge and surround the nucleus of the atom. the protons and electrons are used to calculate the atom's mass whereas the neutrons don't affect the mass