Step 1: Understanding the Concept:
Magnetic materials are broadly classified into three main categories based on their behavioral response in an external magnetic field: diamagnetic, paramagnetic, and ferromagnetic.
Diamagnetic materials develop an induced magnetic dipole moment in a direction strictly opposite to the applied magnetic field and are thus weakly repelled by magnets. Step 2: Key Formula or Approach:
Solving this problem primarily requires factual knowledge of common chemical elements and their standardized magnetic properties at normal room temperature. Step 3: Detailed Explanation:
Let's systematically evaluate the magnetic nature of each given element option.
Option (E) Iron (Fe) and Option (C) Cobalt (Co) are classic and well-known ferromagnetic materials.
Option (B) Gadolinium (Gd) is strongly ferromagnetic at low temperatures but transitions to paramagnetic at room temperature.
Option (D) Sodium (Na) is an alkali metal that typically exhibits paramagnetic properties.
Option (A) Bismuth (Bi) is fundamentally characterized as a strong diamagnetic material. Step 4: Final Answer:
Bi (Bismuth) is the diamagnetic material.