Question

Peroxide ion……
(i) has five completely filled antibonding molecular orbitals
(ii) is diamagnetic
(iii) has bond order one.
(iv) is isoelectronic with neon
Which of the following are correct
A. (iii) and (iv)
B. (i), (ii) and (iv)
C. (i) and (ii)
D. (iv) and (iv)

Answer 1

Correct Answer - C
Peroxide is `O_2^(2-)`
EC=`sigma_(1s)^2 sigma_(1s)^(**2)sigma_(2s)^2 sigma_(2pz)^2 pi_(2py) pi_(2px)^(x^2) pi_(2py)^(x2)`
It has four completely filled antibonding molecular orbitals. It is diamagnetic
Bond order = `1/2`(10-8)=1
Total electrons present=1
`therefore` it is not isoelectronic with `(._(10)Ne)`. Hence, only option (ii) and (iii) are correct,