Choose from the following : `""_(4)Be, ""_(9)F, ""_(19)K, ""_(20)Ca`
Two elements of the same group

Explanation

To determine which two elements from the list belong to the same group, we need to analyze their electronic configurations and identify their valence electrons. Here's a step-by-step solution:

### Step 1: Identify the Elements
The elements given are:
- Beryllium (Be) with atomic number 4
- Fluorine (F) with atomic number 9
- Potassium (K) with atomic number 19
- Calcium (Ca) with atomic number 20
...