Which gas has properties that are most similar to those of an ideal gas

H2

Explanation:

The gas which is considered to be ideal is helium as it has a single atom. Among the options for this question, H2 is the gas which has properties similar to ideal gas.

The characteristics of an ideal gas are:

Molecules of H2 exhibit both these properties hence H2 is the correct option.

a:

by the combination of an unlimited number of elements