In an ionic bond :
=》B. one atom accepts electrons from another.
in this bond an atom ( <em><u>metallic</u></em> ) loses its electrons and another atom ( <em><u>non- metallic</u></em> ) accepts the electrons, and since there isn't the equal positive and negative charges in the atoms, they forms <em><u>cations</u></em> ( +ve charge ) and <em><u>anions </u></em>( -ve charge )
and get stacked or <em><u>attracted</u></em> to each other by strong <em><u>electrostatic force</u></em>.
<span> the atmosphere holds about 21 per cent oxygen. Over the Earth’s 4.6 billion year history, oxygen did not appear in the atmosphere until perhaps about 2.5 billion years ago. Since then, oxygen levels have fluctuated in tandem with global geological and biological events, such as mass extinctions.</span>
carbon atoms form 2 bonds with sharing valence electrons
All elements are pure substances.
The answer is 3. As 5 * 3 = 15.
Is there any other equations I may be able to help you with? :)