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. How many electrons does it take to equal the mass of a dust particle?(1 point)
Responses

6.8×10−40
6 point 8 times 10 to the negative 40 power

1.2×1021
1 point 2 times 10 to the 21th power

6.8×10−41
6 point 8 times 10 to the negative 41 power

1.2×10−21
1 point 2 times 10 to the negative 21 power

8.2×10−20
8 point 2 times 10 to the negative 20 power

8.2×1020

Answer 1

Number = (7.5×10^−10 kg) / (9.1×10^−31 kg) ≈ (7.5/9.1)×10^21 ≈ 0.824×10^21 ≈ 8.2×10^20.

So the correct choice is 8.2×10^20.