What are the oxidation states in Borohydride (BH4-) The CRC Elecrochemical Series and the solution to our exercise suggest that the oxidation states of borohydride are -V for Boron and +I for Hydrogen.

Since H (2.2) is more electronegativ than B (2.0), I would have expected the oxidation states to be +III for B and -I for H.

What am I missing here?

The solution to our exercise lists this (WARNING: it turned out that the solution was wrong):



And the CRC Elecrochemical Series lists this (also suggesting -V for B):
I would have expected the oxidation states to be +III for B and -I for
  H.


You're right, boron is in the (+3) oxidation state in these equations.

In $\ce{B(OH)_3}$ each $\ce{OH}$ is (-1) and the boron is (+3), overall the molecule is neutral

In $\ce{BH_{4}^{-}}$ each $\ce{H}$ is (-1) and the boron is (+3), overall the ion is (-1)