The superscript 4<span> is the atomic mass for </span>helium, and the subscript 2<span> is the atomic number for </span>helium<span>. I hope that will help you.Let me know if need more help on this</span>
1) Calculate the molar weight. 12.000 + 4*(35.45) 2) Divide 15.0 by the molar weight to get moles 3) Multiply by Avogado's number of get the number of molecules.