Which expression correctly represents the proton's mass in kilograms?

Which expression correctly represents the proton's mass in kilograms?

• A. 1 x 10^-30 kilograms
• B. 1 x 10^-28 kilograms
• C. 1 x 10^-27 kilograms
• D. 1 x 10^-26 kilograms

Answer: (C)

Masses at the atomic scale are read in scientific notation, and the proton’s mass is about 1.7 × 10^-27 kilograms. Using 1 × 10^-27 kilograms captures this order of magnitude accurately, since it’s very close to the true value. The other options differ by factors of ten (being either too small or too large), which wouldn’t match the proton’s actual scale. For perspective, that mass is about 1.7 × 10^-24 grams—far lighter than anything you could hold in a typical hand.

Masses at the atomic scale are read in scientific notation, and the proton’s mass is about 1.7 × 10^-27 kilograms. Using 1 × 10^-27 kilograms captures this order of magnitude accurately, since it’s very close to the true value. The other options differ by factors of ten (being either too small or too large), which wouldn’t match the proton’s actual scale. For perspective, that mass is about 1.7 × 10^-24 grams—far lighter than anything you could hold in a typical hand.