Consider the following unbalanced half-reaction: CrO_2 + ?OH -> CrO_4^(-2) + ?H_2O + 3e^-. If the equation were balanced, what would be the coefficient of the water molecule?

$C r {O}_{2} + 4 O {H}^{\text{-}} \to C r {O}_{4}^{- 2} + 2 {H}_{2} O + 2 {e}^{-}$
$C r {O}_{2} + 4 O {H}^{\text{-}} \to C r {O}_{4}^{- 2} + 2 {H}_{2} O + 2 {e}^{-}$