In which of the following hybridisation of underlined atom changes

Options

A. `ulAlH_(3)` changes to `AlH_(4)^(-)`
B. `H_(2)ulO` changes to `H_(3)O^(+)`
C. `ulNH_(3)` changes to `NH_(4)^(+)`
D. in all cases

Answer

A

Explanation

Tips/Formulae:
Hybridisation `=(1)/(2)`[(No. of electron in valence shell of atom) + (No. Of monovalent atom saround it) - (chargeon cation) + ( chargeon anion)]
(a) For `AlH_(3)`,
hybridization of Al atom `=(1)/(2) [3+3-0+0]=3=sp^(2)`
For `AlH_(4)^(-),`
Hybridisation of Al atom `=(1)/(2) [3+4-0+1]=4=sp^(3)`
(b) For `H_(2)O`,
Hybridisation of O atom `=(1)/(2)[6+2-0+0]=4=sp^(3)`
For `H_(3)O^(+)`, Hybridisation of O atom `=(1)/(2)[6+3-1+0]=4=sp^(3)`
For `NH_(3)` Hybridisation of N atom `=(1)/(2)[5+3-0+0]=4sp^(3)`
For `NH_(4)^(+)` Hybridisation of N atom `= (1)/(2)[5+4-1+0]=4=sp^(3)`
Thus hybridization changes only in option (A).