According to the table, which gas would be least efficient-that is, have the least heat-storing ability--for transferring heat from a heat source to a

heat exchanger?

Oxygen

Explanation:

If we had the same question then the table would've given the specific heat for these gases:

Water (steam) | 2.08

Air (25°C) | 1.01

Oxygen | 0.92

Hydrogen | 14.30

Out of these options, oxygen has the lowest specific heat and so it has the least heat-storing ability of the group.