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4. Chemical bonding and molecular structure — Chemistry STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceChemistry4. Chemical bonding and molecular structure1 Mark
MCQ
The molecular electronic configuration of $H_2^ - $ ion is
  • A
    ${\left( {\sigma \,1s} \right)^2}$
  • B
    ${\left( {\sigma \,1s} \right)^2}{\left( {{\sigma ^*}1s} \right)^2}$
  • ✓
    ${\left( {\sigma \,1s} \right)^2}{\left( {{\sigma ^*}1s} \right)^1}$
  • D
    ${\left( {\sigma \,1s} \right)^3}$
✓

Answer

Correct option: C.
${\left( {\sigma \,1s} \right)^2}{\left( {{\sigma ^*}1s} \right)^1}$
c
Total number of electrons in $H _2^{-}$are $3$ so, we can assume that the $H _2^{-}$ molecule is formed by the combination of $H$ and $H ^{-}$ atoms. Therefore, electronic configuration is $1 s ^2 * 1 s ^1$.

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