Question

Total number of electrons present in 48g ${\text{Mg}}^{\text{2+}}$ are:

• A. 24 N${}_{\text{A}}$
• B. 2 N${}_{\text{A}}$
• C. 20 N${}_{\text{A}}$
• D. None of these

Answer 1

Answer: (C)

20 N${}_{\text{A}}$

24 gm of Magnesium contains$=N_A$ atoms. Where $N_A=$ 6.023 $\times$ 10${}^{23}$

48 gm of Mg contains $=2N_A$ atoms.

1 atom of Mg contains 12 electrons

Mg${}^{2+}$ ion will contain $(12–2)=10$ electrons

$2N_A$ $M{g}^{2+}$ ions will contain

$=10\times 2N_A$ electrons

$=10\times 2\times 6.023\times {10}^{23}$

$=20N_A$

Hence, the correct option is $\left(C\right)$.