Which statement about subatomic particles is true?
protons are the only subatomic particles to have charge.
electrons are the subatomic particles with the smallest mass.
neutrons orbit the nucleus of the atom.
subatomic particles all have the same mass.

Electrons are the subatomic particles with the smallest mass.

Explanation:

An atom is the smallest unit of a matter or substance. Every atom consists of three subatomic particles namely electrons, protons and neutrons.

Protons being positively charged and neutrons being electrically neutral are located in the center of an atom where mass of an atom is concentrated.  Both protons and neutrons have nearly same mass.

Atomic mass = Number of protons + Number of neutrons

Electrons being negatively charged are located outside the nucleus where they orbit in different energy levels around the nucleus. and have negligible mass compared to protons and neutrons.