Which of the following is not correct about the hydrides of alkali metals ?

Options

A. They are ionic solids with high melting points.
B. They behave as strong reducing agents and their reducing power increases down the group.
C. These hydrides contain the hydride ion and liberate dihydrogen at the cathode during electrolysis.
D. They react with water and other compounds containing active H atom to liberate dihydrogen.

Answer

C

Explanation

On electrolysis, dihydrogen gas is liberated at the anode :
`2H^(-) toH_(2)(g)+2e^(-)`
(4) `MH(s)+H_(2)O(I)toMOH(aq.)+H_(2)(g)`
`MH(s)+ROH(I)to MOR+H_(2)(g)`
`MH(s)+NH_(3)(g)overset(Delta)toMNH_(2)(s)+H_(2)(g)`
`2MH(s)+CH=CH(g)toMC=CM(s)+2H_(2)(g)`
Lithium hydride is used as a source of hydrogen gas for military purposes and for filling meterological balloons because it has a low molecular mass and, thus, liberates maximum % of `H_(2)(g)` by mass.