What do you mean by 2n2 rule

The maximum number of electrons present in a particular shell is calculated by the formula 2n^2. , where “n” represents the shell number. For instance, K shell is the first shell and it can hold up to 2(1)^2 = 2 electrons. Similarly, L shell is the second shell and it can hold up to 2(2)^2 = 8 electrons.

Explanation:

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it would be a gas formation