<span>I bet this is the notation used in nuclear reactions. The superscript represents the mass number while the subscript represents the atomic number of the element X. So, we find the element with an atomic number of 12. That would be Magnesium or Mg.</span>
Answer:
<em> 1</em>. A. 0
<em>2</em>. B. 7
<em>3. </em>C<em>.</em><em> </em>4
Explanation:
1. charge is equal to the number of protons minus the number of electrons!
2. neutrons is equal to mass number minus atomic number!
3. valence electrons equal 4!
Hope this helped you! :)
