Hey there,
Answer:
4 valence electrons.
Hope this helps :D
<em>~Top☺</em>
<h2><u>Answer</u> :</h2>
The most appropriate option is :

Since, they are the most abundant elements found in Earth's Crust.

E=hc/l
E=
<span><span>E=<span>(6.626 x 10-34 J s)(3.0 x 108m/s )</span><span>=2.88 x 10-19J</span></span><span>6.90 x 10-7m</span></span>
The first step in the scientific methods is ask a question