Approximately how many times larger is the mass of a proton than that of an electron?

• A. 1000 times
• B. 10 times
• C. 100 times
• D. 10000 times

Answer: (A)

Proton mass is about 1.67×10^-27 kg, while electron mass is about 9.11×10^-31 kg, so the ratio is roughly 1836. In round terms, the proton is about two thousand times heavier than an electron, which is closest to a thousand times among the options. The other choices are off by factors of a few, either too small (ten or hundred) or too large (ten thousand). So the best approximation is about a thousand times larger.