Answer:
B. Protons weigh less than neutrons.
Step-by-step explanation:
Option 1: Wrong
The mass of an electron is only about 1/2000 the mass of a proton or neutron, so electrons contribute virtually nothing to the total mass of an atom.
Option 2: Correct
Neutron's second down quark is heavier than the proton's second up quark. So the greater mass of this down quark gives the neutron a greater mass than the proton.
Option 3: Wrong
The proton and neutron have similar, but not identical masses. Either of these particles has a mass approximately 2000 times greater than the mass of an electron. ... The electrons make the greatest contribution to the chemical properties of the atom.
Option 4: Wrong
A neutron is made up of 2 down quarks and 1 up quark, bound together by 3 gluons. A proton is made up of 1 up quark and 2 down quarks, again, bound together by 3 gluons. The up quark is the lightest quark, and any other type is heavier. Both hadrons have 3 gluons, an up and a down quark in common. The only particles left are an up quark from the proton and a down quark from the neutron. Since any other quark is heavier than an up quark, the down quark is heavier. And same+lighter<same+heavier.
A proton and a neutron have a mass approximately 2000 times (x1836) of an electron each.