Question

Which of the following produces hydrolith with dihydrogen?

• A. $Mg$
• B. $Al$
• C. $Cu$
• D. $Ca$

Answer 1

The correct option is D $Ca$

$Ca+H_2\to Ca{H}_2\left(Hydrolith\right)$

During the 1940s, it was used as a source of hydrogen - which continues to this day for
inflating weather balloons etc. It is a saline hydride and does not dissolve in solvents with
which $Ca{H}_2$ does not react.

Also, it reacts violently with water and is thus sometimes used as a desiccant (to remove water
or moisture). Like other saline hydrides (NaH etc.), hydrolith is a reducing agent.