Question

The number of molecules or ions from the following, which do not have odd number of electrons are ______.
(A) NO₂
(B) ICI₄^- 
(C) BrF₃ 
(D) CIO₂ 
(E) NO₂²⁺ 
(F) NO

Hint:

For identifying odd-electron species:
• Calculate the total number of valence electrons, considering charges on ions.
• Species with an odd total number of electrons will have unpaired electrons.

Answer 1

Correct Answer: 3

1. Odd-Electron Species: Odd-electron species have an unpaired electron in their structure, resulting in an odd total number of electrons.
2. Electron Count for Each Species
   \(\text{NO}_2\): 
   \[\text{N (5) + O (6) + O (6) = 17~(odd~electrons).}\]

 \(\text{ICl}_4^-\): 
\(I (7) + 4Cl (4 \times 7) + 1 (charge) = 36~(even~electrons).\)

 \(\text{BrF}_3\): 
\(Br (7) + 3F (3 \times 7) = 28~(even~electrons).\)

 \(\text{ClO}_2\): 
\(\text{Cl (7) + O (6) + O (6) = 19~(odd~electrons).}\)

 \(\text{NO}_2^+\): 
 \[\text{N (5) + O (6) + O (6) - 1 (charge) = 16~(even~electrons).}\]
 \(\text{NO}\): 
 \[\text{N (5) + O (6) = 11~(odd~electrons).}\]
3. Species Without Odd Electrons: The species with an even number of electrons are:
\[\text{ICl}_4^-, \text{BrF}_3, \text{and } \text{NO}_2^+.\]
4. Count: Total number of species without odd electrons: 3.
Final Answer: \(3\).