Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :
- Both Statement I and Statement II are true
- Both Statement I and Statement II are false
- Statement I is true but Statement II is false
- Statement I is false but Statement II is true
Answer
(3) Statement I is true but Statement II is false
Solution
MO configuration of O2 (16 electrons):
1s2 *1s2 2s2 *2s2 2pz2 ( 2px2 = 2py2) ( *2px1 = *2py1)
Bond order = 12(Nb - Na) and the unpaired electrons are those in the *2p orbitals:
O2+ (15 electrons): * electrons = 1 ⇒ B.O. = 2.5, unpaired = 1
O2 (16 electrons): * electrons = 2 ⇒ B.O. = 2, unpaired = 2
O2- (17 electrons): * electrons = 3 ⇒ B.O. = 1.5, unpaired = 1
O22- (18 electrons): * electrons = 4 ⇒ B.O. = 1, unpaired = 0
Statement I: bond length ∝ 1bond order
⇒ bond length: O2+ < O2 < O2- < O22- ∴ Statement I is true.
Statement II: unpaired electrons are 2 (O2), 1 (O2+), 1 (O2-), 0 ( O22-)
∵ O2+ and O2- have the same number (1), the order O2+ > O2- is wrong ∴ Statement II is false.
Answer: (3)