Which of the following gas has the highest thermal conductivity at the same temperature ?

Thermal conductivity is a measure of a material's ability to conduct heat. For gases, thermal conductivity is related to the kinetic energy of the molecules and their ability to transfer this energy through collisions. Lighter gases with higher molecular speeds tend to have higher thermal conductivity. Hydrogen molecules are the lightest and move at the highest speeds among the given options, facilitating more efficient heat transfer.