Some Basic Concepts of Chemistry - Result Question 13
23. How many moles of electron weighs 1 kg ?
(2002, 3M)
(a) $6.023 \times 10^{23}$
(b) $\frac{1}{9.108} \times 10^{31}$
(c) $\frac{6.023}{9.108} \times 10^{54}$
(d) $\frac{1}{9.108 \times 6.023} \times 10^8$
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Answer:
Correct Answer: 23. (d)
Solution:
$\begin{aligned} & \text { 23. Mass of an electron }=9.108 \times 10^{-31} \mathrm{~kg} \\ & \because \quad 9.108 \times 10^{-31} \mathrm{~kg}=1.0 \text { electron } \\ & \begin{aligned} \therefore \quad 1 \mathrm{~kg} & =\frac{1}{9.108 \times 10^{-31}} \text { electrons }=\frac{10^{31}}{9.108} \times \frac{1}{6.023 \times 10^{23}} \\ \quad= & \frac{1}{9.108 \times 6.023} \times 10^8 \text { mole of electrons }\end{aligned}\end{aligned}$
BETA
