How many of the following can dissolve in aqueous HCl as well as in NaOH solution to liberate `H_(2)`? `B,Al,B_(2)H_(6),B_(2)O_(3),NaAlH_(4),Al_(2)O_(3),AlCl_(3),BF_(3)`

Answer

3

Explanation

`Al+3HCltoAlCl_(3)+((3)/(2))H_(2)uarr,Al+NaOH+H_(2)OrarrNaAlO_(2)+((3)/(2))H_(2)uarr`
`B_(2)H_(6)+6HClto3BCl_(3)+6H_(2)uarr,B_(2)H_(6)+6H_(2)Ooverset(NaOH)toH_(3)BO_(3)+6H_(2)uarr`
`NaAlH_(4)+4HCltoNaCl+AlCl_(3)+4H_(2)uarr,NaAlH_(4)`
`underset("excess")overset(NaOH)toNaAlO_(2)(aq)+4H_(2)uarr+2H_(2)O`
Others fail to do so,