Question

The mass of a dust particle is approximately

7.5 x 10-10 kilograms and the mass of an electron
is 9.1 x 10-31 kilograms. Approximately how many
electrons have the same mass as one dust particle?

Answer 1

• 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

Answer 2

Given:

• 
  `\textsf{Mass of a dust particle} = \sf 7.5 * 10^(-10)`

• 
  `\textsf{Mass of an electron} = \sf 9.1 * 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 \frac{\textsf{Mass of a dust particle}}{\textsf{Mass of an electron}} & = \sf (7.5 * 10^(-10))/(9.1 * 10^(-31))\\\\& = \sf (7.5)/(9.1) * (10^(-10))/(10^(-31))\\\\& = \sf 0.8241... * 10^((-10-(-31)))\\\\& = \sf 0.8241... * 10^(21)\\\\& = \sf 8.2 * 10^(20)\end{aligned}`

Therefore, approximately
`\sf 8.2 * 10^(20)` electrons have the same mass as one dust particle.