From a mixture of CO2 and H2 gases, CO2 can be separated by passing the mixture through:

Explanation

Carbon dioxide is separated from hydrogen by passing the mixture through the water under high pressure. When carbon dioxide is compressed into water at pressure, the CO2 gas dissolves into the liquid. When pressure is released, CO2 releases from the liquid as a gas in the form of gas bubbles. This process is also called carbonation and is the basis of many popular beverages. Since hydrogen will not dissolve in the water, the two gases will be effectively separated. Carbon dioxide will not dissolve in the forms of water given in all the remaining options, so separation can not occur, leaving only option B as the correct option.