Neutron Quark Composition

Steps:

• Baryons like protons and neutrons consist of three quarks.
• Up quarks have +2/3 charge; down quarks have -1/3 charge.
• Proton (charge +1) is two up and one down: +2/3 + 2/3 - 1/3 = +1.
• Neutron (charge 0) must be one up and two down: +2/3 - 1/3 - 1/3 = 0.

Why C is correct:

• The standard model defines the neutron as udd to achieve zero charge and match its mass and properties.

Why the others are wrong:

• A (uuu): Yields +2 charge, forming a delta++ baryon, not neutron.
• B (uud): Yields +1 charge, forming a proton.
• D (ddd): Yields -1 charge, forming a delta- baryon.

Final answer: C