When rate of corrosion is maximum?

All of these

The correct answer is option 4. All of these.

The rate of corrosion is maximum when a metal with low standard reduction potential is exposed to an electrolyte in water.

Corrosion is the process of deterioration of a metal by chemical reaction with its environment. The rate of corrosion is affected by a number of factors, including the metal's standard reduction potential, the presence of an electrolyte, and the temperature.

Metals with low standard reduction potentials are more easily oxidized than metals with high standard reduction potentials. This means that they are more likely to lose electrons to the environment and corrode.

Electrolytes are substances that conduct electricity. They can provide the electrons that are needed for the oxidation of a metal. The presence of an electrolyte in water can therefore increase the rate of corrosion.

Temperature also affects the rate of corrosion. Higher temperatures increase the rate of chemical reactions, including the oxidation of metals.

So, the rate of corrosion is maximum when a metal with low standard reduction potential is exposed to an electrolyte in water.

The answer is 4. All of these.