Question

1) Which of the following pairs is isoelectronic?
a)Na+ and Na
b)Mg2+ and Ne
c)A13+ and B3+
d)p3 and N3​

Answer 1

Answer:

The correct options are, (a), (c). (d)

Explanation: Isoelectronic: Atoms, ions, or molecules which have an equal number of valence electrons and the same atom connectivity. Carbon monoxide (CO) and dinitrogen (N2) are isoelectronic. Both have ten valence electrons. Ammonia (NH3) and phosphine (PH3) are isoelectronic.

Answer 2

The correct option is b.

• The species which contains the same number of electrons are isoelectronic.
• The number of electrons in $Na^+$ is 11-1=10 and the number of electrons in Na is 11. So, they are not isoelectronic.
• The number of electrons in $Mg^{+2}$ is 12-2=10 and the number of electrons in Ne is 10. So, they are isoelectronic.
• The number of electrons in $Al^{+3}$ is 13-3=10 and the number of electrons in $B^{+3}$ is 5-3=2. So, they are not isoelectronic.