Magnetic materials — match each class in List I with the correct microscopic ordering description in List II. List I (Class) A. Paramagnetic B. Ferromagnetic C. Antiferromagnetic D. Ferrimagnetic List II (Microscopic description) 1. All dipoles aligned in one preferred direction 2. Half the dipoles aligned oppositely with equal magnitudes (net moment ≈ 0) 3. Sublattices oppose; magnitudes unequal (net moment ≠ 0) 4. All dipoles have equal magnitude but are randomly oriented

Introduction / Context:
Magnetic ordering arises from atomic dipole interactions and crystal structure. Recognizing paramagnetic, ferromagnetic, antiferromagnetic, and ferrimagnetic arrangements helps in materials selection for transformers, recording heads, permanent magnets, and microwave ferrites.

Given Data / Assumptions:

• Room-temperature qualitative descriptions are used.
• “Dipoles” refer to atomic or ionic magnetic moments on crystallographic sublattices.
• We ignore thermal transitions (Curie/Neél temperatures) in this classification task.

Concept / Approach:

Paramagnetism features randomly oriented moments that weakly align with external fields (no long-range order). Ferromagnetism shows parallel alignment of neighboring moments, giving strong net magnetization. Antiferromagnetism has equal and opposite sublattices, cancelling net magnetization. Ferrimagnetism also has opposing sublattices, but unequal magnitudes yield a nonzero net moment (e.g., magnetite Fe3O4).

Step-by-Step Solution:

Verification / Alternative check:

Hysteresis loops: paramagnets show no loop; ferromagnets show large remanence and coercivity; antiferromagnets have near-zero net M; ferrimagnets behave like ferromagnets but with lower saturation due to partial cancellation.

Why Other Options Are Wrong:

• Swapping 2 and 3 confuses antiferromagnetic (equal magnitudes) with ferrimagnetic (unequal magnitudes).
• Assigning order to paramagnets contradicts their random thermal orientation without applied field.

Common Pitfalls:

Thinking ferrimagnetism is just “weak ferromagnetism.” It is distinct: two sublattices oppose with different magnitudes, yielding a net moment and often high Curie temperatures.

Final Answer:

A-4, B-1, C-2, D-3