On passing electricity through an acidified solution of copper (II) sulphate - A. hydrogen ions are reduced at cathode ; B. copper (II) ions are reduced at cathode ; C. copper (II) ions are oxidised at anode ; D. hydorgen gas liberates at cathode .

Options

A. hydrogen ions are reduced at cathode .
B. copper (II) ions are reduced at cathode .
C. copper (II) ions are oxidised at anode .
D. hydorgen gas liberates at cathode .

Answer

To solve the question regarding the electrolysis of an acidified solution of copper (II) sulfate, we need to analyze the reactions occurring at both the cathode and anode during the process. Here’s a step-by-step breakdown of the solution:

### Step 1: Identify the Components
The acidified solution of copper (II) sulfate contains:
- Copper ions (Cu²⁺)
- Sulfate ions (SO₄²⁻)
- Hydrogen ions (H⁺) from the acid

### Step 2: Determine the Reaction at the Cathode
The cathode is the negative electrode where reduction occurs. In this case, the copper ions (Cu²⁺) are attracted to the cathode. The reduction reaction can be written as:
\[ \text{Cu}^{2+} + 2e^- \rightarrow \text{Cu} \]
This means that copper ions gain electrons and are reduced to solid copper (Cu).

### Step 3: Determine the Reaction at the Anode
The anode is the positive electrode where oxidation occurs. The sulfate ions (SO₄²⁻) are stable and do not undergo oxidation. However, hydroxide ions (OH⁻) from water can be oxidized. The oxidation reaction can be written as:
\[ 4\text{OH}^- \rightarrow 2\text{H}_2\text{O} + \text{O}_2 + 4e^- \]
This means that oxygen gas (O₂) is liberated at the anode.

### Step 4: Analyze the Options Given
Now, we will analyze the options provided in the question:
- **A. Hydrogen ions are reduced at cathode**: This is incorrect because copper ions are reduced, not hydrogen ions.
- **B. Copper (II) ions are reduced at cathode**: This is correct as we established that Cu²⁺ ions gain electrons to form copper.
- **C. Copper (II) ions are oxidized at anode**: This is incorrect because copper ions are reduced at the cathode, not oxidized.
- **D. Hydrogen gas liberates at cathode**: This is incorrect because no hydrogen gas is liberated at the cathode; instead, copper is deposited.

### Conclusion
The correct answer is:
**B. Copper (II) ions are reduced at cathode.**