Question

Given below are two statements: Statement (I): The correct sequence of bond lengths in the following species is: \[ O_2^+<O_2<O_2^-<O_2^{2-} \] Statement (II): The correct sequence of number of unpaired electrons in the following species is: \[ O_2>O_2^+>O_2^->O_2^{2-} \] In the light of the above statements, choose the correct answer.

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is true but Statement II is false
• D. Statement I is false but Statement II is true

Answer 1

The Correct Option is A

Concept: Bond length is inversely proportional to bond order. Higher bond order → shorter bond length. Bond order for oxygen species: \[ BO = \frac{N_b - N_a}{2} \]
Step 1:Find bond orders} \[ O_2^+ : BO = 2.5 \] \[ O_2 : BO = 2 \] \[ O_2^- : BO = 1.5 \] \[ O_2^{2-} : BO = 1 \] Thus bond length order: \[ O_2^+<O_2<O_2^-<O_2^{2-} \] Hence Statement I is true.
Step 2:Find number of unpaired electrons} \[ O_2 : 2 \text{ unpaired} \] \[ O_2^+ : 1 \text{ unpaired} \] \[ O_2^- : 1 \text{ unpaired} \] \[ O_2^{2-} : 0 \text{ unpaired} \] Thus general decreasing order: \[ O_2>O_2^+>O_2^->O_2^{2-} \] Hence Statement II is also true. \[ \boxed{\text{Both statements are true}} \]