Which of the following elements is considered magnetic under standard conditions?

• A. Carbon
• B. Cobalt
• C. Chromium
• D. Calcium

Answer: (B)

Verified step by step guidance

1. Understand that magnetism in elements under standard conditions is primarily due to the presence of unpaired electrons in their atomic or electronic structure, which creates a magnetic moment.
2. Recall that elements with partially filled d-orbitals, especially transition metals, often exhibit magnetic properties because their unpaired d-electrons contribute to magnetism.
3. Evaluate each element: Carbon is a non-metal with paired electrons in its common forms, so it is not magnetic; Calcium is an alkaline earth metal with no unpaired d-electrons, so it is not magnetic; Chromium is a transition metal with unpaired electrons but its magnetic behavior is complex and not strongly magnetic under standard conditions.
4. Cobalt is a transition metal with several unpaired d-electrons, which makes it ferromagnetic under standard conditions, meaning it exhibits strong magnetism.
5. Therefore, by comparing the electronic configurations and magnetic properties, identify Cobalt as the element that is magnetic under standard conditions.