Water is decomposed into hydrogen and oxygen by means of an electric current by the method of:

Options

A. electrolysis
B. electric heating
C. electroplating
D. None of these

Explanation

**Step-by-Step Solution:**

1. **Understanding the Process**: The question asks about the method used to decompose water into hydrogen and oxygen using electric current. The correct method for this process is called **electrolysis**.

2. **Setting Up the Electrolysis Apparatus**: To carry out electrolysis, you need an electrolytic tank. In this tank, you will place two electrodes: an **anode** (positive electrode) and a **cathode** (negative electrode). These electrodes are connected to an external battery.

3. **Preparing the Electrolyte**: Pure water is a poor conductor of electricity. To improve its conductivity, you should add a small amount of **dilute acid** (like sulfuric acid) to the water. This will help in the dissociation of water molecules into ions.

4. **Dissociation of Water**: When the electric current passes through the water, it dissociates into **H⁺ (hydrogen ions)** and **OH⁻ (hydroxide ions)**. The H⁺ ions will move towards the cathode, while the OH⁻ ions will move towards the anode.

5. **Oxidation at the Anode**: At the anode, oxidation occurs. The hydroxide ions (OH⁻) lose electrons and are oxidized to form oxygen gas (O₂). The half-reaction can be represented as:
\[ 4OH⁻ \rightarrow 2H₂O + O₂ + 4e⁻ \]

6. **Reduction at the Cathode**: At the cathode, reduction occurs. The hydrogen ions (H⁺) gain electrons to form hydrogen gas (H₂). The half-reaction can be represented as:
\[ 2H⁺ + 2e⁻ \rightarrow H₂ \]

7. **Combining the Reactions**: To get the overall reaction, we combine the two half-reactions. The electrons cancel out, leading to the balanced equation:
\[ 2H₂O \rightarrow 2H₂ + O₂ \]
This shows that two molecules of water decompose into two molecules of hydrogen gas and one molecule of oxygen gas.

8. **Conclusion**: The method used to decompose water into hydrogen and oxygen using electric current is **electrolysis**.

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