Q51 / 180 · NEET 2018 · Chemistry

Consider the following species,

CN+, CN-1, NO and CN

Which one of these will have the highest bond order?

  • A
    CN+
  • Correct answer
    B
    CN-
  • C
    NO
  • D
    CN

Solution

Ion/Species Total electron Bond order
NO 15 2.5
CN- 14 3
CN+ 12 2
CN 13 2.5


Number of e− in NO=7+8=15

NO=σ1s2<σ *1s2<σ2s2<σ *2s2<σ2Pz2<π2Py2=π2Px2<π*2Py1=π *2Px0

Bond order =(number of electron in bonding molecular orbital − number of electron in anti bonding molecular orbital)2

BO=6−12=2.5 .

Number of e− in CN=6+7=13

NO=σ1s2<σ *1s2<σ2s2<σ *2s2<σ2Pz2<π2Py2=π2Px2<π*2Py1=π *2Px0.

Bond order = 5 2 =2.5

Number of e− in CN+=6+7−1=12

NO=σ1s2<σ *1s2<σ2s2<σ *2s2<σ2Pz2<π2Py2=π2Px2<π*2Py1=π *2Px0

Bond order = 4−0 2 =2

CN−= number of e− in CN−=6+7+1=14

CN-=σ1s2<σ *1s2<σ2s2<σ *2s2<σ2Pz2<π2Py2=π2Px2<π*2Py1=π *2Px0

Bond order=6−02=3 .

CN− as highest bond order.

Hence, the correct answer is option: 'B'.

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