Question

Which of the following are isoelectronic species?
(i) $N{H}_3$
(ii) $C{H}_3^{+}$
(ii) $N{H}_2^{-}$
(iv) $N{H}_4^{+}$
Choose the correct answer from the codes given below.

• A. (i), (ii) , (iii)
• B. (ii), (iii), (iv)
• C. (i), (ii), (iv)
• D. (i), (iii), (iv)
• E. (ii), (iii)

Answer 1

Answer: (D)

	Species	Number of electrons
(i)	$N{H}_3$	$7+1\times 3=10$
(ii)	$C{H}_3^{+}$	$6+1\times 3-1=8$
(iii)	$N{H}_2^{-}$	$7+1\times 2+1=10$
(iv)	$N{H}_4^{+}$	$7+1\times 4-1=10$

Since $(i),(iii)$ and $(iv)$ contain equal number of electrons, so these are called isoelectronic species.

(A positive charge means loss of an electron and a negative change means gain of an electron).