What is the actual mass of a neutron?

Correct answer: b 1.675 × 10⁻²⁴ g

By the EV table the neutron's mass is 1.675 × 10⁻²⁴ g, slightly more than the proton's.

Why the other options are wrong

• a 9.11 × 10⁻²⁸ g: This is the electron's mass; the neutron's is 1.675 × 10⁻²⁴ g.
• c 1.673 × 10⁻²⁴ g: This is the proton's mass; the neutron is slightly heavier, 1.675 × 10⁻²⁴ g.
• d 1.60 × 10⁻¹⁹ g: 1.60 × 10⁻¹⁹ is the size of the charge in coulombs, not a mass; the neutron's mass is 1.675 × 10⁻²⁴ g.