what vplume (ml) of hydrogen gas will be produced at STP by the reaction 10.5 g of water and excess Magnesium

The answer is the third choice

Each calcium ion has a charge of +2, which can also be written as ca2+. if those ions move out of the neuron and no other ions are moving, the neuron would lose the positive charge associated with those ions and become more negatively charged.

3is your answer to yuor question