the mass of a dust particle is approximately 7.5×10^−10
kilograms and the mass of an electron is 9.1×10^−31
kilograms. How many electrons does it take to equal the mass of a dust particle?
A. 8.2×10^−20
B. 6.8×10^−40
C. 8.2×10^20
D. 6.8×10^−41
E. 1.2×10^21
F. 1.2×10^−21
To find out how many electrons it takes to equal the mass of a dust particle, we need to divide the mass of the dust particle by the mass of an electron:
(7.5×10^−10) / (9.1×10^−31) = (7.5 / 9.1) × 10^(−10 + 31) = 0.824 × 10^21 = 8.24 × 10^20
Therefore, it takes approximately 8.24 × 10^20 electrons to equal the mass of a dust particle. The closest answer choice is:
C. 8.2×10^20