The Sblock Elements Ques 32
32. All the following substances react with water. The pair that gives the same gaseous product is
[1994]
(a) $K$ and $KO_2$
(b) $Na$ and $Na_2 O_2$
(c) $Ca$ and $CaH_2$
(d) $Ba$ and $BaO_2$
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Solution:
- (c) $Ca$ and $CaH_2$ both react with water to form $H_2$ gas,
$Ca+2 H_2 O \longrightarrow Ca(OH)_2+H_2$
$CaH_2+2 H_2 O \longrightarrow Ca(OH)_2+2 H_2$
whereas
$K$ gives $H_2$ while $KO_2$ gives $O_2$ and $H_2 O_2$
$2 K+2 H_2 O \longrightarrow 2 KOH+H_2$
$2 KO_2+2 H_2 O \longrightarrow 2 KOH+O_2+H_2 O_2$
$2 KO_2+2 H_2 O \longrightarrow 2 KOH+O_2+H_2 O_2$
Similarly, Na gives $H_2$ while $Na_2 O_2$ gives $H_2 O_2$
$2 Na+2 H_2 O \longrightarrow 2 NaOH+H_2$
$Na_2 O_2+2 H_2 O \longrightarrow 2 NaOH+H_2 O_2$
Also, $Ba$ gives $H_2$ while $BaO_2$ gives $H_2 O_2$
$Ba+2 H_2 O \longrightarrow Ba(OH)_2+H_2$
$BaO_2+2 H_2 O \longrightarrow Ba(OH)_2+H_2 O_2$
BETA
