Which of the following gives metal by electrolytic reduction conveniently and profitably?

Options

A. PbO
B. `Fe_2O_3`
C. `Cr_2O_3`
D. `Al_2O_3`

Answer

To determine which process gives metal by electrolytic reduction conveniently and profitably, we need to analyze the types of metals and the processes used for their extraction. Here’s a step-by-step solution:

### Step 1: Understand the Processes
- **Electrolytic Reduction**: This process is typically used for extracting highly reactive metals from their ores. It involves the use of electrical energy to reduce metal ions to their elemental form.
- **Pyrometallurgy**: This method involves the use of high temperatures to extract metals from their ores and is generally used for moderately reactive metals.
- **Hydrometallurgy**: This method uses aqueous solutions to extract metals and is often used for native metals like gold and silver.

### Step 2: Identify the Metals
- **Highly Reactive Metals**: Metals like sodium, potassium, and aluminum are highly reactive and are extracted using electrolytic reduction.
- **Moderately Reactive Metals**: Metals like zinc, copper, and nickel are extracted using pyrometallurgy.
- **Native Metals**: Gold (Au) and silver (Ag) are extracted using hydrometallurgy.

### Step 3: Evaluate Profitability and Convenience
- The profitability of a process is influenced by the cost of extraction and the market value of the metal.
- Electrolytic reduction is generally more expensive due to the energy costs involved, but it is necessary for highly reactive metals.
- For moderately reactive metals, pyrometallurgy is often more convenient and cost-effective.

### Step 4: Conclusion
Based on the analysis, the metals that can be extracted profitably and conveniently by electrolytic reduction are primarily the highly reactive metals. However, for the extraction of moderately reactive metals, pyrometallurgy is often preferred due to lower costs.

### Final Answer
The metals that can be extracted by electrolytic reduction conveniently and profitably are primarily **highly reactive metals** such as aluminum.

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