Which element has the symbol Ni and is ferromagnetic at room temperature?

• A. Nickel
• B. Copper
• C. Iron
• D. Aluminum

Answer: (A)

Nickel is the element with symbol Ni that is ferromagnetic at room temperature. Ferromagnetism arises when magnetic moments align spontaneously and stay aligned after removing an external field. This behavior occurs in certain metals, including nickel, iron, and cobalt, because their magnetic moments remain aligned up to their Curie temperatures. Nickel has a Curie temperature of about 358°C, well above room temperature, so it shows ferromagnetism in everyday conditions. Copper is not ferromagnetic (it’s diamagnetic), and aluminum is only weakly paramagnetic, not ferromagnetic at room temperature. Iron is ferromagnetic too, but its symbol is Fe, not Ni, so the element matching Ni and ferromagnetism at room temperature is nickel.