This is intentionally open ended, use your own definition of best/worst, and explain it.
2 points
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It’s weird to think how someone had to go out of their way to discover something like chlorine gas, considering nowadays most of us have the ingredients to create it sitting in our cupboards.
1 point
Chlorine gas is one thing but you have to mix it with something else to get it to bouyant enough to be dispersable over large areas