Answer :
The best technique to separate copper and iron in a scrap metal yard is by using magnetism. Here's why:
1. **Magnetism**: Iron is attracted to magnets, while copper is not magnetic. By using a magnet, you can easily separate the iron from the copper in the scrap metal. When a magnet is brought close to the mixed metals, the iron will be attracted to the magnet and can be pulled away, leaving the copper behind.
2. **Process**: Simply pass a magnet over the mixed metals, and the iron particles will be attracted to the magnet and separate from the copper. This process is efficient, cost-effective, and commonly used in scrap metal yards to separate different types of metals based on their magnetic properties.
3. **Advantages**: Using magnetism for separation is a quick and effective method that does not require complex equipment or chemicals. It is a straightforward process that can be scaled up for industrial purposes, making it a preferred technique in scrap metal recycling.
By utilizing magnetism, you can efficiently separate copper and iron in a scrap metal yard based on their magnetic properties, making the recycling process more effective and sustainable.