Suppose a gas contains a mixture of the elements hydrogen and helium as shown in Figure 7....

Suppose a gas contains a mixture of the elements hydrogen and helium as shown in Figure 7.1. What fraction of the mass of the gas would be due to the helium atoms it contains?

FIGURE 7.1 The Relative Abundances of Atoms of the Most Common Chemical Elements Elements other than hydrogen and helium can be shown only by using a magnified scale.