Which of the following has maximum value of thermal conductivity?

Thermal conductivity is a measure of a material's ability to conduct heat.

Among the given options — Aluminium, Steel, Brass, and Copper — Copper has the highest thermal conductivity.

Copper is widely used in heat exchangers, electrical wiring, and cookware precisely because of its excellent thermal conductivity.

Typical thermal conductivity values at room temperature are:

Copper: ~400 W/m·K

Aluminium: ~205 W/m·K

Brass: ~110 W/m·K

Steel: ~50 W/m·K

Conclusion: Since Copper has the maximum thermal conductivity among the given materials, Option D is correct.