Question

The species having diamagnetic nature and bond order 1.0 is
a) O2-2
b) O+2
c) F2
d) O2​

Answer 1

Option A is correct

as we know that

bond order = (number of bonding orbital - number of antibonding molecular orbital)/2

hope you get it

Answer 2

Option A is   ie., O2-2

Explanation

First lets see what is diamagnetism ?

"Diamagnetism is a quantum mechanical effect , in chemistry we determine diamagnetism by using Thumb rule . If all the electrons in an atom or molecule  are paired then it is said to be diamagnetic . "

NOW if we see on the oxygen molecules -

Electronic configuration of O2 is 2px1 , 2py1 have one unpaired electron.

Electronic configuration of  O2-2 is 2px2 2py2 have all paired electrons because gain 2 electrons.

Electronic configuration of  O2+2 is 2px1  , one unpaired e-

So that, The molecule O2-2 is Diamagnetic in nature.

We know,

Bond order = [ bonding molecules no. of electrons- antibonding molecules no. of electrons] / 2

Bond order of O2-2 =  10- 8 / 2

Bond order of O2-2  = 1

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