Question

In lithium tetrahydroaluminate (III) the ligand is

• A. $H$
• B. $H^{+}$
• C. $H^{-}$
• D. $Al$

Answer 1

The correct option is C $H^{-}$

Using the rules of nomenclature, we see that the complex is an anion since the name ends with an -ate.
Tetrahydro refers to 4 hydrogens attached to the $Al\left(III\right)$ ion. Remember hydro is hydrogen, hydrato is water! Do not get confused between the two.
Lithium always carries a charge of +1 so the compound looks like this:
The compound would be $Li\left[Al{H}_4\right]$. Clearly, the ion $[Al{H}_4{]}^{-}$ is the complex we are interested in.

So far so good?
Great!
Since $Al\left(III\right)$ ion would have a +3 charge, the charge on the hydrogen would have to be:
$3+4\times hydro=-1$
$\therefore hydro=-1$
Hence the ion in question is $H^{-}$ or the hydride ion.