Write an equation that show the reaction taking place at the cathode?

The general equation for the reaction taking place at the cathode in an electrochemical cell is:

Reduction reaction: A + ne- -> B

Where:
- A represents the substance being reduced at the cathode
- B represents the reduced form of A
- ne- represents the number of electrons involved in the reduction reaction

For example, in the electrolysis of water, the reduction reaction at the cathode can be represented as:

2H+ + 2e- -> H2

This equation shows that two hydrogen ions (H+) are reduced by gaining two electrons (2e-) to form a molecule of hydrogen gas (H2) at the cathode.

Cathodic Reaction:

In acidic solution:

```
2H+ + 2e- → H2
```

In neutral or basic solution:

```
O2 + 2H2O + 4e- → 4OH-
```