Mustard gas (C4H8Cl2S) is a poisonous gas that was used in World War I and banned afterward.

Question:

Mustard gas (C4H8Cl2S) is a poisonous gas that was used in World War I and banned afterward. It causes general destruction of body tissues, resulting in the formation of large water blisters. There is no effective antidote. Calculate the percent composition by mass of the elements in mustard gas.