Which energy change occurs in an operating voltaic cell?
(1) chemical to electrical
(2) electrical to chemical
(3) chemical to nuclear
(4) nuclear to chemical

Answer : The correct option is, (1) chemical to electrical

Explanation :

Voltaic cell : It is a device that is used for the conversion of the chemical energy produces in a redox reaction into the electrical energy.

For example : The redox reaction occurs between the zinc and copper sulfate.

In the voltaic cell, the oxidation occurs at an anode which is a negative electrode and the reduction occurs at the cathode which is a positive electrode.

The balanced two-half reactions will be,

Oxidation half reaction :

Reduction half reaction :

Thus the overall reaction will be,

Hence, the correct option is, (1) chemical to electrical

where is the following

explanation:

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%