a total of three shells, with two electrons in its valence shell?

Explanation

To solve the question regarding an element that has a total of three shells with two electrons in its valence shell, we can follow these steps:

### Step 1: Understand Electron Shells
An atom has several electron shells, which are energy levels where electrons reside. The first shell (K shell) can hold a maximum of 2 electrons, the second shell (L shell) can hold a maximum of 8 electrons, and the third shell (M shell) can also hold a maximum of 18 electrons.

**Hint:** Remember the maximum number of electrons each shell can hold: K=2, L=8, M=18.

### Step 2: Identify the Valence Shell
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