The mass of a dust particle is approximately 7.5x10^-10 kilograms and the mass of an electron is 9.1x10^-31 kilograms. How many electrons does it take to equal the mass of a dust particle?
A. 6.8x10^-41
B. 6.8x10^-40
C. 1.2x10^-21
D. 8.2x10^20
E. 8.2x10^-20
F. 1.2x10^21
To find the number of electrons it takes to equal the mass of a dust particle, we can divide the mass of the dust particle by the mass of a single electron:
(7.5x10^-10 kg) / (9.1x10^-31 kg/electron)
= 8.24x10^20 electrons
Therefore, the closest answer choice is D. 8.2x10^20.