If a stimulus opens ligand-gated sodium ion channels, the neuron will

The neuron will depolarize, if a stimulus opens ligand-gated sodium ion channels. Depolarize in other words is to remove or reduce the polarization of, also to cause to become partially or wholly unpolarized. If a stimulus will open ligand-gated sodium ion channels, the neuron will depolarize.

Cr(oh)3 -> cr(3+) + 3oh-

Less stable  hope this