How Electrodes with their ions are arranged in an Electrochemical series?

In an increasing order of their standard reduction potential.

The correct answer is: 2. In an increasing order of their standard reduction potential.

In an Electrochemical series, the electrodes and their respective ions are arranged in an increasing order of their standard reduction potential. The standard reduction potential of an electrode measures its ability to gain electrons and undergo reduction. A higher reduction potential indicates a stronger tendency for the electrode to be reduced and act as a cathode in an electrochemical cell.

The Electrochemical series is a useful tool in electrochemistry as it allows us to compare the relative reactivity of different electrodes and predict the direction of spontaneous redox reactions in electrochemical cells. The standard reduction potential values are typically given with respect to the standard hydrogen electrode (SHE), which has a defined potential of 0.00 volts.

Option 1, "In decreasing order of their standard reduction potential," is incorrect as the Electrochemical series is arranged in increasing order of standard reduction potential.

Option 3, "In an increasing order of their standard oxidation potential," is also incorrect as the Electrochemical series is based on the standard reduction potential and not the standard oxidation potential.

Option 4, "All of these," is not correct because only option 2 is accurate for describing how the Electrochemical series is arranged.

Therefore, the correct answer is option 2: In an increasing order of their standard reduction potential.