For getting the result of this problem, the knowledge of periodic table is very important. From the periodic table we come to know that. The knowledge of atomic mass of magnesium is also required to solve the problem.
1 mole of magnesium = 24.3 gm
88.1 moles of magnesium = (24.3 * 88.1) gms
= 2140.83 gms
So 2140.83 grams are there in 88.1 moles of magnesium.