Question

How many moles of electrons weigh one kilogram?

(Mass of electron = $9.108\times {10}^{-31}kg$; Avagadro number = $6.023\times {10}^{23}kg$)

• A. $\frac{1}{9.108\times 6.023}\times {10}^8$
• B. $6.023\times {10}^{23}$
• C. $\frac{1}{9.108}\times {10}^{31}$
• D. $\frac{6.023}{9.108}\times {10}^{54}$

Answer 1

The correct option is A $\frac{1}{9.108\times 6.023}\times {10}^8$

Mass of electron $9.108\times {10}^{-31}kg$.
The number of electrons that weigh 1 kg will be $\frac{1}{9.108\times {10}^{-31}}$
The Avagadro number is $6.023\times {10}^{23}$.
The number of moles of electrons that weigh 1 kg will be
$\frac{1}{9.108\times {10}^{-31}\times 6.023\times {10}^{23}}=\frac{1}{9.108\times 6.023}\times {10}^8$