Need answer subatomic particle has the least mass?
a.
a proton
c.
an electron
b.
a neutron
d.
a nucleus

-- A nucleus is a cluster of protons and neutrons.

-- Every proton has the same mass, and every neutron has the
same mass. 

-- The mass of a proton and the mass of a neutron are almost identical.

-- The mass of either a proton or a neutron is the same as the mass
of more than 1,800 electrons.


This is the same answer that I posted earlier.  A very reliable Mod
came along and deleted my answer, and said there was something
wrong with it but didn't say what was wrong.  I'm convinced that what
I've said so far is accurate, so I'm posting it again.

Maybe the problem with the answer the first time was that I didn't go
to the finish line and say "So the is the one with the least mass."
I felt that you could easily figure it out from everything I've said so far.
But just in case you can't, or if THAT's what the Mod didn't like last time,
then here it is:

     So, of the items on your list of choices, the subatomic
     particle that has the least mass is the electron.