Which statement correctly describes electrochemical cells? A. Electrochemical cells involve only oxidation reactions.

B. Electrochemical cells involve only reduction reactions.

C. Electrochemical cells involve oxidation-reduction reactions.

D. Electrochemical cells do not involve oxidation-reduction reactions.​

C. Electrochemical cells involve oxidation-reduction reactions.

Explanation: Oxidation occurs at the anode, and reduction occurs at the cathode.

answer: a chemical reaction

explanation:

im not wrong

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%