Question

Particle A has very little mass in comparison to Particle B. Both particles are in the same atom. Which is the best conclusion about Particles A and B?

Answer 1

Particle A orbits the nucleus, and Particle B is located in the nucleus.

Step-by-step explanation:

Answer 2

Particle-A is an electron, racing around in a cloud that's far from the nucleus.

Particle-B is either a proton or a neutron, in the nucleus.

The big clue is where you said that particle-A has very little mass
compared to particle-B. Protons and neutrons have almost identical
masses, but it's the same mass as more than 1,800 electrons !