Question

The mass of a dust particle is approximately

Answer 1

Answer:

Given:

• $\textsf{Mass of a dust particle} = \sf 7.5 \times 10^{-10}$

• $\textsf{Mass of an electron} = \sf 9.1 \times 10^{-31}$

To calculate how many electrons have the same mass as one dust particle, divide the mass of a dust particle by the mass of an electron:

$\begin{aligned}\implies \dfrac{\textsf{Mass of a dust particle}}{\textsf{Mass of an electron}} & = \sf \dfrac{7.5 \times 10^{-10}}{9.1 \times 10^{-31}}\\\\& = \sf \dfrac{7.5}{9.1} \times \dfrac{10^{-10}}{10^{-31}}\\\\& = \sf 0.8241... \times 10^{(-10-(-31))}\\\\& = \sf 0.8241... \times 10^{21}\\\\& = \sf 8.2 \times 10^{20}\end{aligned}$

Therefore, approximately $\sf 8.2 \times 10^{20}$ electrons have the same mass as one dust particle.

Answer 2

• Mass of dust=7.5×10^{-10}kg
• Mass of electron=9.1×10^{-31}kg

Total electrons

• Mass of dust/Mass of electron
• 7.5×10^{-10}\9.1×10^{-31}
• 0.824×10²¹
• 8.25×10²⁰