The thermal conductivity is expressed as

Explanation:

The correct answer is option 1 i.e W⋅ m-1⋅ K-1.

The thermal conductivity of a material is a measure of its ability to conduct heat.

The system of Unit (SI unit) of thermal conductivity is measured in Watts per meter-kelvin (W/(m⋅K).

We know that,

1 watt = 1 Joule per second =J.s-1.

∴SI unit of thermal conductivity can be rewritten as:

\(Joule.Second^{-1} \over Meter.Kelvin\)= J⋅ s-1⋅ m-1⋅ K-1  or W⋅ m-1⋅ K-1.