Question

Thermal conductivity is lower for

• A. $\text{Wood}$
• B. $\text{Air}$
• C. $\text{Water at}{100}^{\circ }C$
• D. $\text{Steam at}1\text{bar}$

Answer 1

The correct option is B $\text{Air}$

$\begin{array}{cc}\text{Material}& \text{Thermal conductivity: kW/mk}\\ \text{Wood (wood fire)}& \text{0.11}\\ \text{Air}\left({20}^{\circ }C\right)& \text{0.025}\\ \text{Water (}{100}^{\circ }C)& \text{0.6804}\\ \text{Steam}(1bar\text{\&}{200}^{\circ }C)& \text{0.03349}\end{array}$
Note: Thermal conductivity of gasses is lowest among all materials