MCQ
Which of the following facts given is not correct ?
$(I)$ Bond length order : $H^-_2 = H^+_2 > H_2$

$(II)\, O^+_2 ,NO,N^-_2$ have same bond order of $2 \frac{1}{2}$

$(III)$ Bond order can assume any value including zero upto four

$(IV)\, NO^-_3$ and $BO^-_3$ have same bond order for $X - O$ bond (where $X$ is central atom)

  • A
    $I, II$ & $III$
  • $I$ & $IV$
  • C
    $II$ & $IV$
  • D
    $I$ & $II$

Answer

Correct option: B.
$I$ & $IV$
b
Bond order $=\frac{1}{2}$ [Number of bonding electrons $-$ Number of anti bonding electrons]

$I)$ Bond order of $H _2^{-}=\frac{1}{2}[2-1]=0.5$

Bond order of $H _2^{+}=\frac{1}{2}[1-0]=0.5$

Bond order of $H _2=\frac{1}{2}[2-0]=1$

Bond order of $H _2$ is greater than $H _2^{-}$and $H _2^{+}$

$II)$ Bond order of $O _2^{+}=\frac{1}{2}[10-5]=2.5$

Bond order of $NO =\frac{1}{2}[10-5]=2.5$

Bond order of $N _2^{-}=\frac{1}{2}[10-5]=2.5$

$III)$ Bond order can have any value. And a bond order equal to zero implies

that there is no bond at all between the atoms.

$IV) \,NO _3^{-}$and $BO _3^{-}$ do not have same bond order.

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