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?(1 point)
Responses
A. 6.8×10^−40
B. 1.2×10^21
C. 8.2×10^−20
D. 6.8×10^−41
E. 1.2×10^−21
F. 8.2×10^20
B. 1.2×10^21
To find the number of electrons it takes to equal the mass of a dust particle, divide the mass of the dust particle by the mass of an electron:
(7.5×10^-10 kg) / (9.1×10^-31 kg) = (7.5 / 9.1) x 10^(-10 - (-31)) = 0.824 x 10^21 = 1.2 x 10^21
Therefore, it takes approximately 1.2 x 10^21 electrons to equal the mass of a dust particle.