Tag: the structure of atoms

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Questions Related to the structure of atoms

Multiple choice chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

How many moles of electron weighs one kilogram?

  1. $6.023\times 10^{23}$
  2. $\dfrac {1}{9.108}\times 10^{31}$
  3. $\dfrac {6.023}{9.108}\times 10^{54}$
  4. $\dfrac {1}{9.108\times 6.023}\times 10^8$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mass of one electron is $9.108\times 10^{-31} kg$.


Mass of one mole of electrons is ${9.108 \times 10^{-31} \times 6.023}\times 10^{23}={9.108\times 6.023}\times 10^{-8}$.

Thus, $1$ kg corresponds to $\dfrac {1}{9.108\times 6.023}\times 10^8$ moles of electrons.

Hence, the correct option is $D$

Multiple choice chemistry atom fundamental particles of an atom the structure of atoms discovery of subatomic particles

How many moles of electrons weigh one kilogram? 

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

  1. $\displaystyle \frac{1}{9.108\times 6.023}\times 10^{8} $
  2. $\displaystyle 6.023\times 10^{23}$
  3. $\displaystyle \frac{1}{9.108}\times 10^{31}$
  4. $\displaystyle \frac{6.023}{9.108}\times 10^{54}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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