Question

${\mathrm{Mg}}^{2+}$ is isoelectronic with

• A. ${\mathrm{Cu}}^{2+}$
• B. ${\mathrm{Ca}}^{2+}$
• C. ${\mathrm{Na}}^{+}$
• D. ${\mathrm{Zn}}^{2+}$

Answer 1

The correct option is C

${\mathrm{Na}}^{+}$

Explanation for correct answers:

Option C ${\mathrm{Na}}^{+}$

• The isoelectronic species have the same number of electrons.
• The atomic number of Magnesium is 12.
• A cation may be defined as an atom or molecule that is positively charged.
• Positively charged elements are formed when the metal loses electrons.
• The number of the electron in ${\mathrm{Mg}}^{2+}$is $12-2=10$
• The number of the electron in ${\mathrm{Na}}^{+}$ is $11-1=10$
• Hence option C ${\mathrm{Na}}^{+}$is correct.

The explanation for incorrect answers:

Option A ${\mathrm{Cu}}^{2+}$

• The atomic number of Copper is 29.
• The number of electrons in ${\mathrm{Cu}}^{2+}$ is $29-2=27$.
• Hence option A ${\mathrm{Cu}}^{2+}$is incorrect.

Option B ${\mathrm{Ca}}^{2+}$

• The atomic number of Calcium is 20.
• The number of electrons in ${\mathrm{Ca}}^{2+}$ is $20-2=18$.
• Hence option B ${\mathrm{Ca}}^{2+}$is Incorrect.

Option D ${\mathrm{Zn}}^{2+}$

• The atomic number of Zinc is 30.
• The number of electrons in ${\mathrm{Zn}}^{2+}$ is $30-2=28$.
• Hence option D ${\mathrm{Zn}}^{2+}$is incorrect.