C) a fundamental force would be gravity
Americium has a molar mass of 243 g/mol.
There are 6.022*10^23 atoms in a mol (Avogadro's number).
6 atoms / 6.022 * 10^23 atoms/mol gives us:
9.963*10^-24 mols
Lastly: 9.963*10^-24 mols * 243 g/mol = 2.42*10^-21 g
Answer:
11.6 grams of MgO can be produced with 4.63 grams of oxygen.
Explanation:

Mass of oxygen gas = 4.63 g
Moles of oxygen gas = 
According to reaction, 1 mole of oxygen gas gives 2 moles of magnesium oxide, then 0.1447 moles of oxygen gas will giv e:
of magnesium oxide
Mass of 0.2894 moles of magnesium oxide:
= 0.29 mol × 40 g/mol = 11.6 g
11.6 grams of MgO can be produced with 4.63 grams of oxygen.