Question

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. Which expression would you use to find out how many electrons you need to equal the mass of one dust particle?(1 point)
Responses

(7.5×10−10)÷(9.1×10−31)
open paren 7 point 5 times 10 to the negative 10 power close paren divided by open paren 9 point 1 times 10 to the negative 31 power close paren

(9.1×10−31)(7.5×10−10)
open paren 9 point 1 times 10 to the negative 31 power close paren times open paren 7 point 5 times 10 to the negative 10 power close paren

(9.1×10−31)÷(7.5×10−10)
open paren 9 point 1 times 10 to the negative 31 power close paren divided by open paren 7 point 5 times 10 to the negative 10 power close paren

(7.5×10−10)(9.1×10−31)
open paren 7 point 5 times 10 to the negative 10 power close paren times open paren 9 point 1 times 10 to the negative 31 power close paren

(9.1×10−31)−(7.5×10−10)
open paren 9 point 1 times 10 to the negative 31 power close paren minus open paren 7 point 5 times 10 to the negative 10 power close paren
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Answer 1

You divide the dust-particle mass by the electron mass:

(7.5×10^−10) ÷ (9.1×10^−31)

Numerically: (7.5/9.1)×10^(21) ≈ 8.24×10^20 electrons.