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The P-Block Elements

Question
CBSEENCH12011063

Which of the following options represents the correct order? 

  • O2-> O2>O2+

  • O2-<O2<O2+

  • O2->O2<O2+

  • O2-<O2>O2+

Solution

B.

O2-<O2<O2+

Bond order of O2-
straight O subscript 2 superscript minus space equals space straight sigma 1 straight s squared comma space straight sigma asterisk times 1 straight s squared comma straight sigma 2 straight s squared comma straight sigma asterisk times 2 straight s squared space straight sigma 2 straight p subscript straight z superscript 2 left parenthesis straight pi 2 straight p subscript straight x superscript 2 space equals space straight pi 2 straight p subscript straight y superscript 2 right parenthesis space left parenthesis straight pi asterisk times 2 straight p subscript straight x superscript 2 space equals space straight pi asterisk times 2 straight p subscript straight y superscript 1 right parenthesis
Bond space order
equals
fraction numerator Number space of space electrons space in space BMO minus space Number space of space electron space ABMO over denominator 2 end fraction
equals space fraction numerator 10 minus 7 over denominator 2 end fraction space equals space 3 over 2 space equals space 15
straight O subscript 2 superscript plus space equals space straight sigma 1 straight s squared comma space straight sigma asterisk times 1 straight s squared comma straight sigma 2 straight s squared comma straight sigma asterisk times 2 straight s squared space straight sigma 2 straight p subscript straight z superscript 2 left parenthesis straight pi 2 straight p subscript straight x superscript 2 space equals space straight pi 2 straight p subscript straight y superscript 2 right parenthesis space left parenthesis straight pi asterisk times 2 straight p subscript straight x superscript 1 space equals space straight pi asterisk times 2 straight p subscript straight y superscript 0 right parenthesis
BO space equals space fraction numerator 10 minus 5 over denominator 2 end fraction space equals space 5 over 2 space equals space 2.5
straight O subscript 2 space equals space space straight sigma 1 straight s squared comma space straight sigma asterisk times 1 straight s squared comma straight sigma 2 straight s squared comma straight sigma asterisk times 2 straight s squared space straight sigma 2 straight p subscript straight z superscript 2 left parenthesis straight pi 2 straight p subscript straight x superscript 2 space equals space straight pi 2 straight p subscript straight y superscript 2 right parenthesis space left parenthesis straight pi asterisk times 2 straight p subscript straight x superscript 1 space equals space straight pi asterisk times 2 straight p subscript straight y superscript 1 right parenthesis

straight B. straight O space equals space fraction numerator 10 minus 6 over denominator 2 end fraction space equals space 4 over 2 space equals space 2
so comma space the space correct space order space is comma
straight O subscript 2 superscript minus space less than space straight O subscript 2 space less than space straight O subscript 2 superscript plus