🔍 Key Concepts
• Edison (nickel–iron) batteries are alkaline storage batteries, not lead‑acid
• They are called nickel–iron because the two plate materials are different metals/compounds
• Each answer choice talks about what the plates are made of – look for which statements can all be true at the same time
💭 Think About
• Think about why the Edison battery is also called a nickel–iron cell. Does that suggest one metal, two metals on separate plates, or a single combined compound?
• Does an Edison battery have only nickel plates, only iron plates, or one type for the positive and another for the negative?
• If one choice says "all of the above," check carefully whether every earlier statement about plate materials can be correct together, or if any one of them is too specific or incomplete.
✅ Before You Answer
• Verify what metal/compound is used for the positive plate in a nickel–iron (Edison) cell.
• Verify what metal/compound is used for the negative plate in a nickel–iron (Edison) cell.
• Check whether any choice describes only one of the plate materials; if so, ask yourself whether that can make "all of the above" true.