Avoltaic cell with an aqueous electrolyte is based on the reaction between cd2+(aq) and mg(s), producing cd(s) and mg2+(aq). write half-reactions for the anode and cathode and then write a balanced cell reaction. include the states of matter in the equations.

half-reactions

cathode : Cd²⁺ (aq) + 2e⁻ ---> Cd (s)

anode :  Mg (s) → Mg²⁺ (aq) + 2e−

a balanced cell reaction

Cd²⁺(aq) + Mg(s)→ Cd(s) + Mg²⁺ (aq)

Further explanation

Cell potential (E °) is the potential difference between the two electrodes in an electrochemical cell.

Electric current moves from a high potential pole to a low potential, so the cell potential is the difference between an electrode that has a high electrode potential (cathode) and an electrode that has a low electrode potential (anode)

or:

E ° cell = E ° reduction-E ° oxidation

(At the cathode the reduction reaction occurs, the anode oxidation reaction occurs)

The value of E cells uses a reference electrode which is used as a comparison called the Standard Electrode which is the hydrogen-platinum electrode

In reaction:

Cd²⁺ + Mg → Cd + Mg²⁺

half-reactions

 at the cathode (reduction reaction) Cd²⁺ (aq) + 2e⁻ ---> Cd (s)   at the anode (oxidation reaction) Mg (s) → Mg²⁺ (aq) + 2e−

a balanced cell reaction

Cd²⁺(aq) + Mg(s)→ Cd(s) + Mg²⁺ (aq)

Learn more

The standard cell potential

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The answer is b.the gaseous state is electrically positive, while the plasma state is electrically negative. 

As newton's first law states a object in motion stays in motion