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Q. Which of the following chemicals does not liberate hydrogen gas on reaction with aluminium metal?

COMEDKCOMEDK 2015The p-Block Elements

Solution:

Dilute and concentrated $HNO _3$ has no effect on Al, Aluminium is rendered passive by nitric acid due to the fopnation of a thin. film of oxide $\left( Al _2 O _3\right)$ on its surface.
Aluminium dissolves in dil. $HCl$ and liberates dihydrogen. $2 Al _{( S )}+6 HCl _{( aq )} \longrightarrow 2 Al _{( aq )}^{3+}+6 Cl -{ }_{( aq )}+3 H _{2( g )}$
Aluminium also reacts with aqueous alkali and liberates dihydrogen.
$2 Al _{( S )}+2 NaOH _{( aq )}+6 H _2 O _{( l )} \longrightarrow 2 Na \left[ Al ( OH )_4\right]_{( aq )}+3 H _{2( g )} $
$2 Al +6 HNO _{3( conc )} \longrightarrow Al _2 O _3+6 NO _2+3 H _2 O$
$2 Al +6 H _2 SO _4 \longrightarrow Al _2\left( SO _4\right)_3+3 SO _2+6 H _2 O$