Question

Which of the following reaction produces hydrogen?

• A. $Mg + H _{2} O$
• B. $H _{2} S _{4} O _{8}+ H _{2} O$
• C. $BaO _{2}+ HCl$
• D. $Na _{2} O _{2}+2 HCl$

Answer 1

Answer: (A)

Alkali and alkaline earth metals react with water to produce hydrogen gas and metal hydroxide. This is due to their high electropositive character.

$2 Na +2 H _{2} O \longrightarrow 2 NaOH + H _{2}$

$Mg +2 H _{2} O \longrightarrow Mg ( OH )_{2}+ H _{2}$