Question

How many moles of electrons weigh one kilogram? (Mass of electron $=9.108\times {10}^{-31}kg$, Avogadro’s number $=6.023\times {10}^{23}$)

• A.
• B.
• C.
• D.

Answer 1

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

$1e^{-}=9.108\times {10}^{-31}kg$
1 mole of $e^{-}=9.108\times {10}^{-31}\times 6.023\times {10}^{23}kg$
$?=1kg(1\times {10}^{3}g)$

$=\frac{1\times {10}^{3}g}{9.108\times {10}^{-31}\times 6.023\times {10}^{23}}$

$=\frac{1}{9.108\times 6.023}\times {10}^{8}moles$