Question

Noble gases are inert because they have completed outer electron shells. Which of these elements isn't a noble gas?

Answer 1

Nsmte __/\__

At the top of the noble gases is little helium (He), with a shell that is full with only two electrons. The fact that their outer shells are full means they are quite happy and don't need to react with other elements. In fact, they rarely combine with other elements. That non-reactivity is why they are called inert.

Answer 2

Answer:

                             CHLORINE                    

REASON;

Chlorine is not a noble gas. It's one electron shy of a full octet, so unlike the noble gases, it's highly reactive.

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