Faraday's second law of electrolysis is related to which of the following?

Equivalent weight of electrolyte.

The answer is 4. Equivalent weight of electrolyte.

Faraday's second law of electrolysis states that the masses of different ions liberated at the electrodes when the same quantity of electricity is passed through different electrolytes are directly proportional to their equivalent weights.

The equivalent weight of an element is the mass of that element that combines with or displaces 1 gram of hydrogen. It is a measure of the reactivity of an element.

So, Faraday's second law of electrolysis is related to the equivalent weight of the electrolyte because the amount of an ion that is liberated at an electrode is directly proportional to its equivalent weight.

The other options are incorrect. The atomic number of an ion does not affect the amount of that ion that is liberated at an electrode. The speed of ions is also not related to the amount of an ion that is liberated at an electrode.