Atypical carbon atom has six protons, six neutrons, and six electrons. which of these has the least amount of mass?

a) one proton
b) one neutron
c) six electrons
d) these masses are too tiny to measure

six electrons

Explanation:

Electrons have almost virtually no mass and much less than a proton and neutron.  

(a neutron and electron have about 1 amu while electrons have 0.000548 amu)

the positions which points up in upward carbon and down in downward carbon are axial

and vice versa holds true for equatorial positions

so the correct answer with labelled diagram will be